AWS VPN connections are used to extend on-premises data centers to AWS.
VPN connections provide secure IPSec connections between the data center or branch office and the AWS resources.
AWS Site-to-Site VPN or AWS Hardware VPN or AWS Managed VPN
Connectivity can be established by creating an IPSec, hardware VPN connection between the VPC and the remote network.
On the AWS side of the VPN connection, a Virtual Private Gateway (VGW) or Transit Gateway provides two VPN endpoints for automatic failover.
On the customer side, a customer gateway (CGW) needs to be configured, which is the physical device or software application on the remote side of the VPN connection
AWS Client VPN is a managed client-based VPN service that enables secure access to AWS resources and resources in the on-premises network.
AWS VPN CloudHub
For more than one remote network e.g. multiple branch offices, multiple AWS hardware VPN connections can be created via the VPC to enable communication between these networks
AWS Software VPN
A VPN connection can be created to the remote network by using an EC2 instance in the VPC that’s running a third-party software VPN appliance.
AWS does not provide or maintain third-party software VPN appliances; however, there is a range of products provided by partners and open source communities.
AWS Direct Connect provides a dedicated private connection from a remote network to the VPC. Direct Connect can be combined with an AWS hardware VPN connection to create an IPsec-encrypted connection
AWS Site-to-Site VPN Options (2025)
As of November 2025, AWS Site-to-Site VPN includes five distinct options:
Standard VPN with VGW – Up to 1.25 Gbps per tunnel; terminates on a Virtual Private Gateway.
Standard VPN with TGW or Cloud WAN – Up to 1.25 Gbps per tunnel; terminates on a Transit Gateway or AWS Cloud WAN. Supports ECMP for higher aggregate bandwidth.
Large Bandwidth Tunnel with TGW – Up to 5 Gbps per tunnel (launched November 2025); a 4x improvement over the standard 1.25 Gbps limit. Ideal for bandwidth-intensive hybrid applications, big data migrations, and disaster recovery.
VPN Concentrator – Simplifies multi-site connectivity for distributed enterprises (launched November 2025). Supports up to 100 low-bandwidth remote sites (under 100 Mbps each) through a single Transit Gateway attachment with 5 Gbps aggregate bandwidth.
Accelerated VPN – Uses AWS Global Accelerator to route traffic through the nearest AWS edge location, reducing internet distance and improving performance. Supported on Transit Gateway.
Private IP VPN – Enables Site-to-Site VPN connections over AWS Direct Connect using private IP addresses. Encrypts DX traffic between on-premises networks and AWS without traversing the public internet. Requires Transit Gateway.
VPN Components
Virtual Private Gateway – VGW
A virtual private gateway is the VPN concentrator on the AWS side of the VPN connection
Supports standard bandwidth (up to 1.25 Gbps per tunnel)
Does not support IPv6 for Site-to-Site VPN connections
Does not support ECMP
Customer Gateway – CGW
A customer gateway is a physical device or software application on the customer side of the VPN connection.
When a VPN connection is created, the VPN tunnel comes up when traffic is generated from the remote side of the VPN connection.
By default, VGW is not the initiator; CGW must bring up the tunnels for the Site-to-Site VPN connection by generating traffic and initiating the Internet Key Exchange (IKE) negotiation process.
If the VPN connection experiences a period of idle time, usually 10 seconds, depending on the configuration, the tunnel may go down. To prevent this, a network monitoring tool to generate keepalive pings; for e.g. by using IP SLA.
Transit Gateway
A transit gateway is a transit hub that can be used to interconnect VPCs and on-premises networks.
A Site-to-Site VPN connection on a transit gateway can support either IPv4 traffic or IPv6 traffic inside the VPN tunnels.
Supports ECMP (Equal Cost Multi-Path) routing for aggregating bandwidth across multiple VPN tunnels (up to 50 Gbps).
Supports large bandwidth tunnels (up to 5 Gbps per tunnel).
Supports IPv6 addresses for outer tunnel IPs (announced July 2025), enabling full IPv6 migration (IPv6-in-IPv6) and IPv4-in-IPv6 configurations.
Supports VPN Concentrator attachments for multi-site connectivity.
Supports Private IP VPN connections over Direct Connect.
AWS Cloud WAN
AWS Cloud WAN is a managed wide area networking service for building and managing global networks.
Site-to-Site VPN connections can be attached to Cloud WAN core networks for global hybrid connectivity.
Supports IPv6 outer tunnel IPs (same as Transit Gateway).
A Site-to-Site VPN connection offers two VPN tunnels between a VGW or a transit gateway on the AWS side, and a CGW (which represents a VPN device) on the remote (on-premises) side.
VPN Routing Options
For a VPN connection, the route table for the subnets should be updated with the type of routing (static or dynamic) that you plan to use.
Route tables determine where network traffic is directed. Traffic destined for the VPN connections must be routed to the virtual private gateway.
The type of routing can depend on the make and model of the CGW device
Static Routing
If your device does not support BGP, specify static routing.
Using static routing, the routes (IP prefixes) can be specified that should be communicated to the virtual private gateway.
Devices that don’t support BGP may also perform health checks to assist failover to the second tunnel when needed.
BGP Dynamic Routing
If the VPN device supports Border Gateway Protocol (BGP), specify dynamic routing with the VPN connection.
When using a BGP device, static routes need not be specified to the VPN connection because the device uses BGP for auto-discovery and to advertise its routes to the virtual private gateway.
BGP-capable devices are recommended as the BGP protocol offers robust liveness detection checks that can assist failover to the second VPN tunnel if the first tunnel goes down.
Only IP prefixes known to the virtual private gateway, either through BGP advertisement or static route entry, can receive traffic from the VPC.
Virtual private gateway does not route any other traffic destined outside of the advertised BGP, static route entries, or its attached VPC CIDR.
VPN Route Priority
Longest prefix match applies.
If the prefixes are the same, then the VGW prioritizes routes as follows, from most preferred to least preferred:
BGP propagated routes from an AWS Direct Connect connection
Manually added static routes for a Site-to-Site VPN connection
BGP propagated routes from a Site-to-Site VPN connection
Prefix with the shortest AS PATH is preferred for matching prefixes where each Site-to-Site VPN connection uses BGP
Path with the lowest multi-exit discriminators (MEDs) value is preferred when the AS PATHs are the same length and if the first AS in the AS_SEQUENCE is the same across multiple paths.
VPN Bandwidth and Throughput
Standard VPN Tunnel: Up to 1.25 Gbps per tunnel (default)
Large Bandwidth VPN Tunnel: Up to 5 Gbps per tunnel (available on Transit Gateway, launched November 2025)
Supports modifying tunnel bandwidth on existing VPN connections (announced May 2026) without changing IP addresses, CIDR blocks, or pre-shared keys
VPN Concentrator Tunnel: Up to 100 Mbps per tunnel, 5 Gbps aggregate per concentrator
ECMP (Transit Gateway): Up to 50 Gbps aggregate bandwidth using multiple VPN tunnels with ECMP configured (each flow limited to max bandwidth per tunnel)
Many factors affect realized bandwidth including packet size, traffic mix (TCP/UDP), shaping or throttling policies on intermediate networks, internet weather, and specific application requirements.
VPN Limitations
supports only IPSec tunnel mode. Transport mode is currently not supported.
supports only one VGW can be attached to a VPC at a time.
does not support IPv6 traffic on a virtual private gateway. (IPv6 is supported on Transit Gateway and Cloud WAN.)
does not support Path MTU Discovery.
does not support overlapping CIDR blocks for the networks. It is recommended to use non-overlapping CIDR blocks.
does not support transitive routing. So for traffic from on-premises to AWS via a virtual private gateway, it
does not support Internet connectivity through Internet Gateway
does not support Internet connectivity through NAT Gateway
does not support VPC Peered resources access through VPC Peering
However, Internet connectivity through NAT instance and VPC Interface Endpoint or PrivateLink services are accessible.
provides a bandwidth of 1.25 Gbps per tunnel for standard VPN connections. Large bandwidth tunnels support up to 5 Gbps per tunnel on Transit Gateway.
MTU is 1446 bytes and MSS is 1406 bytes. Jumbo frames are not supported.
VPN Tunnel Endpoint Lifecycle Control
The VPN Tunnel Endpoint Lifecycle Control feature enables scheduling endpoint replacements at a time that aligns with business and operational needs, prior to the service-mandated deadline.
Provides advanced notice of upcoming maintenance updates to help plan and minimize service disruptions.
When enabled, AWS notifies before performing tunnel endpoint replacements.
Users can accept the maintenance update at a convenient time or let it apply automatically by the deadline.
During a tunnel endpoint update, AWS applies replacement to one tunnel at a time to ensure continuous connectivity.
Available in most AWS commercial and GovCloud regions.
VPN Monitoring
AWS Site-to-Site VPN automatically sends notifications to the AWS Health Dashboard
AWS Site-to-Site VPN is integrated with CloudWatch with the following metrics available
TunnelState
The state of the tunnels.
For static VPNs, 0 indicates DOWN and 1 indicates UP.
For BGP VPNs, 1 indicates ESTABLISHED and 0 is used for all other states.
For both types of VPNs, values between 0 and 1 indicate at least one tunnel is not UP.
TunnelDataIn
The bytes received on the AWS side of the connection through the VPN tunnel from a customer gateway.
This metric counts the data after decryption.
TunnelDataOut
The bytes sent from the AWS side of the connection through the VPN tunnel to the customer gateway.
This metric counts the data before encryption.
ConcentratorBandwidthUsage
The bandwidth usage for a Site-to-Site VPN Concentrator connection.
Available only for VPN connections using a VPN Concentrator.
Units: Bits per second
Site-to-Site VPN Logs
VPN logs can be published to Amazon CloudWatch Logs for detailed analysis of VPN connection activity.
Provides tunnel activity logs for troubleshooting connectivity issues.
Amazon CloudWatch Network Synthetic Monitor
Supports hybrid monitors for networking built with AWS Direct Connect and AWS Site-to-Site VPN.
Provides proactive monitoring of hybrid connectivity health.
IPv6 Support for Site-to-Site VPN
Inner Tunnel IPv6: Supported on Transit Gateway and Cloud WAN. Allows IPv4 or IPv6 traffic inside VPN tunnels.
Outer Tunnel IPv6 (July 2025): Site-to-Site VPN now supports IPv6 addresses for outer tunnel IPs on Transit Gateway and Cloud WAN connections.
Enables full IPv6 migration with IPv6 addresses for both outer tunnel IPs and inner packet IPs (IPv6-in-IPv6).
Helps customers with IPv6-only network mandates meet regulatory and compliance needs.
IPv6 VPNs support the same throughput (Gbps and PPS), MTU, and route limits as IPv4 VPNs.
Note: Virtual private gateways do NOT support IPv6 for Site-to-Site VPN connections. IPv6 requires Transit Gateway or Cloud WAN.
VPN Concentrator (November 2025)
AWS Site-to-Site VPN Concentrator simplifies multi-site connectivity for distributed enterprises with many low-bandwidth remote sites.
Suitable for customers needing to connect 25+ remote sites to AWS, with each site needing low bandwidth (under 100 Mbps).
Allows up to 100 remote sites to connect through a single VPN Concentrator attachment to AWS Transit Gateway.
Provides 5 Gbps aggregate bandwidth shared across all connected sites.
Eliminates the need to deploy and manage multiple virtual appliances for HA and connectivity.
AWS manages high availability across multiple Availability Zones.
Can be used with eero integration for simplified remote site connectivity without manual tunnel configuration.
Quotas:
Up to 50 VPN Concentrators per Region
Up to 5 VPN Concentrators per Transit Gateway or Cloud WAN
Up to 100 remote sites per VPN Concentrator
VPN Connection Redundancy
A VPN connection is used to connect the customer network to a VPC.
Each VPN connection has two tunnels to help ensure connectivity in case one of the VPN connections becomes unavailable, with each tunnel using a unique virtual private gateway public IP address.
Both tunnels should be configured for redundancy.
When one tunnel becomes unavailable, for e.g. down for maintenance, network traffic is automatically routed to the available tunnel for that specific VPN connection.
To protect against a loss of connectivity in case the customer gateway becomes unavailable, a second VPN connection can be set up to the VPC and virtual private gateway by using a second customer gateway.
Customer gateway IP address for the second VPN connection must be publicly accessible.
By using redundant VPN connections and CGWs, maintenance on one of the customer gateways can be performed while traffic continues to flow over the second customer gateway’s VPN connection.
Dynamically routed VPN connections using the Border Gateway Protocol (BGP) are recommended, if available, to exchange routing information between the customer gateways and the virtual private gateways.
Statically routed VPN connections require static routes for the network to be entered on the customer gateway side.
BGP-advertised and statically entered route information allows gateways on both sides to determine which tunnels are available and reroute traffic if a failure occurs.
Multiple Site-to-Site VPN Connections
VPC has an attached virtual private gateway, and the remote network includes a customer gateway, which must be configured to enable the
VPN connection.
Routing must be set up so that any traffic from the VPC bound for the remote network is routed to the virtual private gateway.
Each VPN has two tunnels associated with it that can be configured on the customer router, as is not a single point of failure
Multiple VPN connections to a single VPC can be created, and a second CGW can be configured to create a redundant connection to the same external location or to create VPN connections to multiple geographic locations.
VPN CloudHub
VPN CloudHub can be used to provide secure communication between multiple on-premises sites if you have multiple VPN connections
VPN CloudHub operates on a simple hub-and-spoke model using a Virtual Private gateway in a detached mode that can be used without a VPC.
Design is suitable for customers with multiple branch offices and existing
Internet connections who’d like to implement a convenient, potentially low-cost hub-and-spoke model for primary or backup connectivity between these remote offices
Note: For large-scale multi-site connectivity (25+ sites), consider using the newer VPN Concentrator feature with Transit Gateway, which provides a managed, scalable alternative.
VPN CloudHub architecture with blue dashed lines indicates network
traffic between remote sites being routed over their VPN connections.
AWS VPN CloudHub requires a virtual private gateway with multiple customer gateways.
Each customer gateway must use a unique Border Gateway Protocol (BGP) Autonomous System Number (ASN)
Customer gateways advertise the appropriate routes (BGP prefixes) over their VPN connections.
Routing advertisements are received and re-advertised to each BGP peer, enabling each site to send data to and receive data from the other sites.
Routes for each spoke must have unique ASNs and the sites must not have overlapping IP ranges.
Each site can also send and receive data from the VPC as if they were using a standard VPN connection.
Sites that use AWS Direct Connect connections to the virtual private gateway can also be part of the AWS VPN CloudHub.
To configure the AWS VPN CloudHub,
multiple customer gateways can be created, each with the unique public IP address of the gateway and the ASN.
a VPN connection can be created from each customer gateway to a common virtual private gateway.
each VPN connection must advertise its specific BGP routes. This is done using the network statements in the VPN configuration files for the VPN connection.
Private IP VPN over Direct Connect
AWS Site-to-Site VPN Private IP VPN enables deploying VPN connections over Direct Connect using private IP addresses.
Direct Connect provides a private, dedicated connection but is not encrypted. Private IP VPN adds IPSec encryption to DX traffic.
Requires a Transit Gateway with a Direct Connect Gateway attachment.
Traffic stays on the AWS private network and never traverses the public internet.
Satisfies security and compliance regulations requiring encryption at layer 3 for dedicated connections.
Configuration:
Create or use an existing Transit Gateway with a private IP CIDR block.
Establish a Direct Connect connection and Transit VIF to a Direct Connect Gateway.
Create a Private IP VPN connection specifying private outside IP address type.
Accelerated Site-to-Site VPN
An accelerated VPN connection uses AWS Global Accelerator to route traffic from the on-premises network to the nearest AWS edge location.
Reduces the distance over which data is shared on the internet by leveraging the AWS global fiber network.
Improves performance for VPN connections where the customer gateway is geographically distant from the AWS Region.
Requires a Transit Gateway (not supported on VGW).
Each accelerated VPN connection uses two Global Accelerator resources (one per tunnel).
Default quota: 10 accelerated Site-to-Site VPN connections per Region (adjustable).
Virtual private gateways per Region: 5 (adjustable)
Site-to-Site VPN connections per Region: 50 (adjustable)
Site-to-Site VPN connections per virtual private gateway: 10 (adjustable)
Accelerated VPN connections per Region: 10 (adjustable)
Large Bandwidth Tunnel connections per Region: 50 (adjustable)
VPN Concentrators per Region: 50 (adjustable)
VPN Concentrators per Transit Gateway or Cloud WAN: 5 (adjustable)
Remote sites per VPN Concentrator: 100 (adjustable)
Dynamic routes advertised from CGW to VPN on VGW: 100 (not adjustable)
Routes advertised from VPN on VGW to CGW: 1,000 (not adjustable)
Dynamic routes advertised from CGW to VPN on Transit Gateway: 1,000 (not adjustable)
Routes advertised from VPN on Transit Gateway to CGW: 5,000 (not adjustable)
AWS Certification Exam Practice Questions
Questions are collected from Internet and the answers are marked as per my knowledge and understanding (which might differ with yours).
AWS services are updated everyday and both the answers and questions might be outdated soon, so research accordingly.
AWS exam questions are not updated to keep up the pace with AWS updates, so even if the underlying feature has changed the question might not be updated
Open to further feedback, discussion and correction.
You have in total 5 offices, and the entire employee-related information is stored under AWS VPC instances. Now all the offices want to connect the instances in VPC using VPN. Which of the below help you to implement this?
you can have redundant customer gateways between your data center and your VPC
you can have multiple locations connected to the AWS VPN CloudHub
You have to define 5 different static IP addresses in route table.
1 and 2
1,2 and 3
You have in total of 15 offices, and the entire employee-related information is stored under AWS VPC instances. Now all the offices want to connect the instances in VPC using VPN. What problem do you see in this scenario?
You can not create more than 1 VPN connections with single VPC (Can be created)
You can not create more than 10 VPN connections with single VPC (soft limit can be extended)
When you create multiple VPN connections, the virtual private gateway can not sends network traffic to the appropriate VPN connection using statically assigned routes. (Can route the traffic to correct connection)
Statically assigned routes cannot be configured in case of more than 1 VPN with the virtual private gateway. (can be configured)
None of above
You have been asked to virtually extend two existing data centers into AWS to support a highly available application that depends on existing, on-premises resources located in multiple data centers and static content that is served from an Amazon Simple Storage Service (S3) bucket. Your design currently includes a dual-tunnel VPN connection between your CGW and VGW. Which component of your architecture represents a potential single point of failure that you should consider changing to make the solution more highly available?
Add another VGW in a different Availability Zone and create another dual-tunnel VPN connection.
Add another CGW in a different data center and create another dual-tunnel VPN connection. (Refer link)
Add a second VGW in a different Availability Zone, and a CGW in a different data center, and create another dual-tunnel.
No changes are necessary: the network architecture is currently highly available.
You are designing network connectivity for your fat client application. The application is designed for business travelers who must be able to connect to it from their hotel rooms, cafes, public Wi-Fi hotspots, and elsewhere on the Internet. You do not want to publish the application on the Internet. Which network design meets the above requirements while minimizing deployment and operational costs? [PROFESSIONAL]
Implement AWS Direct Connect, and create a private interface to your VPC. Create a public subnet and place your application servers in it. (High Cost and does not minimize deployment)
Implement Elastic Load Balancing with an SSL listener that terminates the back-end connection to the application. (Needs to be published to internet)
Configure an IPsec VPN connection, and provide the users with the configuration details. Create a public subnet in your VPC, and place your application servers in it. (Instances still in public subnet are internet accessible)
Configure an SSL VPN solution in a public subnet of your VPC, then install and configure SSL VPN client software on all user computers. Create a private subnet in your VPC and place your application servers in it. (Cost effective and can be in private subnet as well. Note: AWS Client VPN is the managed alternative for this use case.)
You are designing a connectivity solution between on-premises infrastructure and Amazon VPC Your server’s on-premises will De communicating with your VPC instances You will De establishing IPSec tunnels over the internet You will be using VPN gateways and terminating the IPsec tunnels on AWS-supported customer gateways. Which of the following objectives would you achieve by implementing an IPSec tunnel as outlined above? (Choose 4 answers) [PROFESSIONAL]
End-to-end protection of data in transit
End-to-end Identity authentication
Data encryption across the Internet
Protection of data in transit over the Internet
Peer identity authentication between VPN gateway and customer gateway
Data integrity protection across the Internet
A development team that is currently doing a nightly six-hour build which is lengthening over time on-premises with a large and mostly under utilized server would like to transition to a continuous integration model of development on AWS with multiple builds triggered within the same day. However, they are concerned about cost, security and how to integrate with existing on-premises applications such as their LDAP and email servers, which cannot move off-premises. The development environment needs a source code repository; a project management system with a MySQL database resources for performing the builds and a storage location for QA to pick up builds from. What AWS services combination would you recommend to meet the development team’s requirements? [PROFESSIONAL]
A Bastion host Amazon EC2 instance running a VPN server for access from on-premises, Amazon EC2 for the source code repository with attached Amazon EBS volumes, Amazon EC2 and Amazon RDS MySQL for the project management system, EIP for the source code repository and project management system, Amazon SQL for a build queue, An Amazon Auto Scaling group of Amazon EC2 instances for performing builds and Amazon Simple Email Service for sending the build output. (Bastion is not for VPN connectivity also SES should not be used)
An AWS Storage Gateway for connecting on-premises software applications with cloud-based storage securely, Amazon EC2 for the resource code repository with attached Amazon EBS volumes, Amazon EC2 and Amazon RDS MySQL for the project management system, EIPs for the source code repository and project management system, Amazon Simple Notification Service for a notification initiated build, An Auto Scaling group of Amazon EC2 instances for performing builds and Amazon S3 for the build output. (Storage Gateway does provide secure connectivity but still needs VPN. SNS alone cannot handle builds)
An AWS Storage Gateway for connecting on-premises software applications with cloud-based storage securely, Amazon EC2 for the resource code repository with attached Amazon EBS volumes, Amazon EC2 and Amazon RDS MySQL for the project management system, EIPs for the source code repository and project management system, Amazon SQS for a build queue, An Amazon Elastic Map Reduce (EMR) cluster of Amazon EC2 instances for performing builds and Amazon CloudFront for the build output. (Storage Gateway does not provide secure connectivity, still needs VPN. EMR is not ideal for performing builds as it needs normal EC2 instances)
A VPC with a VPN Gateway back to their on-premises servers, Amazon EC2 for the source-code repository with attached Amazon EBS volumes, Amazon EC2 and Amazon RDS MySQL for the project management system, EIPs for the source code repository and project management system, SQS for a build queue, An Auto Scaling group of EC2 instances for performing builds and S3 for the build output. (VPN gateway is required for secure connectivity. SQS for build queue and EC2 for builds)
A company has 50 branch offices and wants to connect all of them to AWS. Each branch has bandwidth requirements under 50 Mbps. Which AWS VPN solution is most cost-effective and operationally simple?
Create 50 individual Site-to-Site VPN connections to a Transit Gateway (Works but higher cost and operational overhead with 50 separate VPN connections)
Use a VPN Concentrator on Transit Gateway to connect all branches through a single attachment (VPN Concentrator supports up to 100 sites with under 100 Mbps each, single TGW attachment simplifies management)
Use VPN CloudHub with a Virtual Private Gateway (VPN CloudHub works but limited to VGW capabilities and doesn’t scale as easily)
A company requires encrypted connectivity between their on-premises data center and AWS over their existing Direct Connect connection. The traffic must not traverse the public internet. Which solution meets these requirements?
Configure a standard Site-to-Site VPN over the internet as backup to Direct Connect (Traffic traverses the public internet)
Configure a Private IP VPN connection over Direct Connect using Transit Gateway (Private IP VPN encrypts DX traffic using private IP addresses without internet traversal)
Enable MACsec on Direct Connect and use VGW for VPN termination (MACsec provides L2 encryption but VGW doesn’t support Private IP VPN)
Use AWS Client VPN over Direct Connect (Client VPN is for remote user access, not site-to-site connectivity)
A company needs to migrate large datasets to AWS and requires more than 1.25 Gbps of VPN bandwidth per tunnel. What should they configure?
Create multiple standard VPN connections and enable ECMP on a VGW (VGW does not support ECMP)
Use Accelerated VPN with Global Accelerator to increase per-tunnel bandwidth (Accelerated VPN improves latency but does not increase per-tunnel bandwidth beyond standard limits)
Configure a Large Bandwidth Tunnel VPN connection on Transit Gateway for up to 5 Gbps per tunnel (Large Bandwidth Tunnels support up to 5 Gbps per tunnel on TGW)
Configure Direct Connect with 10 Gbps dedicated connection (Meets bandwidth needs but is not a VPN solution and takes longer to provision)
An organization has VPN connections from multiple branch offices to AWS. The VPN performance is poor because the branches are far from the AWS Region. What can improve VPN performance without changing the on-premises equipment? (Choose 2)
Enable Accelerated VPN using AWS Global Accelerator on Transit Gateway (Routes traffic to the nearest AWS edge location to reduce internet distance)
Enable VPN CloudHub on a Virtual Private Gateway (VPN CloudHub is for inter-site communication, not for improving performance)
Use Large Bandwidth Tunnels (5 Gbps) on Transit Gateway (Higher per-tunnel bandwidth can improve throughput for bandwidth-constrained connections)
Configure Private IP VPN over Direct Connect (Requires Direct Connect infrastructure, changes the connectivity model)
Add more VPN tunnels with ECMP on VGW (VGW does not support ECMP)
VPC Endpoints enable the creation of a private connection between VPC to supported AWS services and VPC endpoint services powered by PrivateLink using its private IP address
Traffic between VPC and AWS service does not leave the Amazon network
Endpoints are virtual devices, that are horizontally scaled, redundant, and highly available VPC components that allow communication between instances in the VPC and AWS services without imposing availability risks or bandwidth constraints on your network traffic.
AWS currently supports the following types of Endpoints
VPC Gateway Endpoints – target for a route in a route table (S3 and DynamoDB only, free)
VPC Resource Endpoints (GA Dec 2024) – direct access to VPC resources (e.g., RDS, EC2 instances, IP/domain targets) across accounts without a load balancer
Gateway Load Balancer Endpoints – route traffic to network virtual appliances (firewalls, IDS/IPS) deployed behind a Gateway Load Balancer
A VPC Gateway Endpoint is a gateway that is a target for a specified route in the route table, used for traffic destined for a supported AWS service.
Gateway Endpoints currently supports S3 and DynamoDB services only.
Gateway Endpoints do not require an Internet gateway or a NAT device for the VPC.
Gateway endpoints do not enable AWS PrivateLink.
Gateway Endpoints are available at no additional charge.
Gateway Endpoints do not support cross-region requests – they must be created in the same Region as the S3 bucket or DynamoDB table.
Gateway Endpoints do not allow access from on-premises networks, from peered VPCs in other AWS Regions, or through a Transit Gateway. Use Interface Endpoints for those scenarios.
VPC Endpoint policy and Resource-based policies can be used for fine-grained access control.
S3 Gateway Endpoints now support IPv6 (announced November 2025) – both dual-stack and IPv6-only configurations are supported.
VPC Interface endpoints enable connectivity to services powered by AWS PrivateLink.
Services include AWS serviceslike CloudTrail, CloudWatch, etc., services hosted by other AWS customers and partners in their own VPCs (referred to as endpoint services), and supported AWS Marketplace partner services.
Interface Endpoints only allow traffic from VPC resources to the endpoints and not vice versa.
PrivateLink endpoints can be accessed across both intra- and inter-region VPC peering connections, Direct Connect, and VPN connections.
VPC Interface Endpoints, by default, have an address like vpce-svc-01234567890abcdef.us-east-1.vpce.amazonaws.com which needs application changes to point to the service.
Private DNS name feature allows consumers to use AWS service public default DNS names which would point to the private VPC endpoint service.
Interface Endpoints can be used to create custom applications in VPC and configure them as an AWS PrivateLink-powered service (referred to as an endpoint service) exposed through a Network Load Balancer.
Custom applications can be hosted within AWS or on-premises (via Direct Connect or VPN)
Interface Endpoints are billed per hour per AZ provisioned, plus per-GB data processing charges. See AWS PrivateLink Pricing.
Cross-Region PrivateLink (GA November 2024)
AWS PrivateLink now supports native cross-region connectivity, breaking the previous limitation that VPC endpoints were regional-only.
As a service consumer, you can privately connect to VPC endpoint services hosted in other AWS Regions within the same partition, without cross-region peering or exposing data to the public internet.
As a service provider, you can offer your endpoint service to customers in all Regions from a single Region without deploying infrastructure in each Region.
Cross-region connectivity for custom endpoint services (customer-hosted) launched Nov 2024.
Cross-region connectivity for AWS services (e.g., S3, ECR, Route 53) launched Nov 2025.
Traffic remains on the AWS backbone and does not traverse the public internet.
Available within the same AWS partition (commercial, GovCloud, China) across all supported Regions.
VPC Resource Endpoints (GA December 2024)
Resource Endpoints are a new type of VPC endpoint introduced at re:Invent 2024 that provide private access to specific VPC resources across accounts.
Resource Endpoints allow you to privately access a resource (e.g., an RDS database, EC2 instance, IP address, or domain name) in another VPC without requiring a Network Load Balancer.
A VPC resource is represented by a resource configuration, which is associated with a resource gateway.
Resources can be shared across accounts using AWS Resource Access Manager (RAM).
Supports TCP traffic only (UDP is not supported).
Network connections must be initiated from the VPC containing the resource endpoint (unidirectional).
Currently supported ARN-based resources include Amazon RDS instances.
Also supports connectivity to any resource by IP address or domain name target.
DNS names are automatically provisioned with format: endpoint_id.rcfgId.randomHash.vpc-lattice-rsc.region.on.aws
Private DNS is supported for ARN-based resources (e.g., RDS), allowing continued use of the resource’s original DNS name.
Supports IPv4, IPv6, and dual-stack addressing.
Integrates with Amazon VPC Lattice for advanced service networking scenarios.
Billed per hour per endpoint provisioned, plus per-GB data processing. Resource gateways billed per-GB data processed.
Gateway Load Balancer Endpoints
Gateway Load Balancer (GWLB) Endpoints provide private connectivity between your VPC and network virtual appliances (firewalls, IDS/IPS, deep packet inspection) deployed in a service provider VPC behind a Gateway Load Balancer.
GWLB Endpoints serve as an entry/exit point in your VPC for traffic inspection.
Used as a target in route tables to transparently route traffic through security appliances.
Each GWLB endpoint can support up to 10 Gbps per AZ and auto-scales up to 100 Gbps.
Supports ingress routing from Internet Gateway and Virtual Private Gateway for inline traffic inspection.
Commonly used in centralized security inspection architectures with AWS Transit Gateway.
S3 VPC Endpoints Strategy
S3 is now accessible with both Gateway Endpoints and Interface Endpoints.
Gateway Endpoint – Free, route-table based, same-Region only, no on-premises or cross-region access. Recommended for most in-Region workloads.
Interface Endpoint – Hourly + per-GB charges, ENI-based, accessible from on-premises (via Direct Connect/VPN), across VPC peering, Transit Gateway, and now cross-region (via Cross-Region PrivateLink, Nov 2025).
Both Gateway and Interface VPC Endpoints for S3 now support IPv6 (November 2025).
VPC Endpoint Policies & Security
VPC Endpoint policies control which AWS principals can use the endpoint to access the service.
Endpoint policies can be attached to Gateway, Interface, and Resource endpoints.
Security groups can be attached to Interface and Resource endpoints to control inbound/outbound traffic.
New IAM Condition Keys (August 2025) for organization-wide network perimeter controls:
aws:VpceAccount – Restrict requests based on the account that owns the VPC endpoint.
aws:VpceOrgID – Restrict based on the AWS Organization ID of the endpoint owner.
aws:VpceOrgPaths – Restrict based on organizational unit paths of the endpoint owner.
These new keys complement the existing aws:sourceVpce and aws:sourceVpc condition keys and enable scalable network perimeter controls across entire AWS Organizations without hard-coding VPC endpoint IDs.
AWS Certification Exam Practice Questions
Questions are collected from Internet and the answers are marked as per my knowledge and understanding (which might differ with yours).
AWS services are updated everyday and both the answers and questions might be outdated soon, so research accordingly.
AWS exam questions are not updated to keep up the pace with AWS updates, so even if the underlying feature has changed the question might not be updated
Open to further feedback, discussion and correction.
You have an application running on an Amazon EC2 instance that uploads 10 GB video objects to amazon S3. Video uploads are taking longer than expected inspite of using multipart upload cause of internet bandwidth, resulting in poor application performance. Which action can help improve the upload performance?
Apply an Amazon S3 bucket policy
Use Amazon EBS provisioned IOPS
Use VPC endpoints for S3
Request a service limit increase
What are the services supported by VPC endpoints, using Gateway endpoint type? Choose 2 answers
Amazon S3
Amazon EFS
Amazon DynamoDB
Amazon Glacier
Amazon SQS
What are the different types of endpoint types supported by VPC endpoints? Choose 2 Answers [Note: As of 2024, AWS now supports additional endpoint types including Resource Endpoints and Gateway Load Balancer Endpoints. This question reflects the original SAA exam scope.]
Gateway
Classic
Interface
Virtual
Network
An application running on EC2 instances processes sensitive information stored on Amazon S3. The information is accessed over the Internet. The security team is concerned that the Internet connectivity to Amazon S3 is a security risk. Which solution will resolve the security concern?
Access the data through an Internet Gateway.
Access the data through a VPN connection.
Access the data through a NAT Gateway.
Access the data through a VPC endpoint for Amazon S3.
You need to design a VPC for a three-tier architecture, a web application consisting of an Elastic Load Balancer (ELB), a fleet of web/application servers, and a backend consisting of an RDS database. The entire Infrastructure must be distributed over 2 availability zones. Which VPC configuration works while assuring the least components are exposed to Internet?
Two public subnets for ELB, two private subnets for the web-servers, two private subnets for RDS and DynamoDB
Two public subnets for ELB and web-servers, two private subnets for RDS and DynamoDB
Two public subnets for ELB, two private subnets for the web-servers, two private subnets for RDS and VPC Endpoints for DynamoDB
Two public subnets for ELB and web-servers, two private subnets for RDS and VPC Endpoints for DynamoDB
A company needs to access Amazon S3 buckets in a different AWS Region privately without exposing traffic to the public internet. Which solution should they use?
Use Gateway VPC Endpoints for cross-region S3 access
Use Interface VPC Endpoints with Cross-Region PrivateLink for S3
Set up VPC peering between regions and use Gateway Endpoints
Use AWS Direct Connect with public VIF
A SaaS provider needs to give customers in multiple AWS accounts private access to an Amazon RDS database without deploying a Network Load Balancer. Which solution meets this requirement?
Create a VPC peering connection to each customer account
Use an Interface VPC Endpoint with an NLB in front of the RDS instance
Create a resource configuration for the RDS instance and share it via AWS RAM, allowing customers to create Resource Endpoints
Use AWS Transit Gateway to connect all customer VPCs
A security team wants to ensure that all API requests from their AWS Organization pass through their organization’s VPC endpoints, without hard-coding individual endpoint IDs in policies. Which approach should they use?
Use aws:sourceVpce condition key with wildcard values
Use aws:sourceVpc condition key listing all VPC IDs
Use aws:VpceOrgID condition key to validate requests originate from endpoints owned by their organization
AWS NAT – Network Address Translation devices, launched in the public subnet, enables instances in a private subnet to connect to the Internet but prevents the Internet from initiating connections with the instances.
Instances in private subnets would need an internet connection for performing software updates or trying to access external services.
NAT device performs the function of both address translation and port address translation (PAT)
NAT instance prevents instances to be directly exposed to the Internet and having to be launched in a Public subnet and assigning of the Elastic IP address to all, which are limited.
NAT device routes the traffic, from the private subnet to the Internet, by replacing the source IP address with its address and it translates the address back to the instances’ private IP addresses for the response traffic.
AWS allows NAT configuration in 2 ways
NAT Gateway, managed service by AWS (recommended)
NAT Instance (legacy, not recommended)
NAT Gateway
NAT gateway is an AWS managed NAT service that provides better availability, higher bandwidth, and requires less administrative effort.
A NAT gateway supports 5 Gbps of bandwidth and automatically scales up to 100 Gbps. For higher bursts requirements, the workload can be distributed by splitting the resources into multiple subnets and creating a NAT gateway in each subnet.
A NAT gateway can process one million packets per second and automatically scales up to ten million packets per second. Beyond this limit, a NAT gateway will drop packets.
Each NAT gateway is created in a specific Availability Zone and implemented with redundancy in that zone (for zonal NAT gateways).
A NAT gateway supports the TCP, UDP, and ICMP protocols.
NAT gateways are supported for IPv4 or IPv6 traffic. For IPv6 traffic, NAT gateway performs NAT64. By using this in conjunction with DNS64 (available on Route 53 Resolver), IPv6 workloads in a subnet can communicate with IPv4 resources.
NAT gateway cannot be associated with a security group. Security can be configured for the instances in the private subnets to control the traffic.
Network ACL can be used to control the traffic to and from the subnet. NACL applies to the NAT gateway’s traffic, which uses ports 1024-65535
NAT gateway when created receives an elastic network interface that’s automatically assigned a private IP address from the IP address range of the subnet. Attributes of this network interface cannot be modified.
NAT gateway cannot send traffic over VPC endpoints, VPN connections, AWS Direct Connect, or VPC peering connections. The private subnet’s route table should be modified to route the traffic directly to these devices.
NAT gateway can route traffic to Transit Gateways and virtual private gateways (for private NAT gateways) or through Transit Gateway for Site-to-Site VPN/Direct Connect traffic.
NAT gateway times out the connection if it is idle for 350 seconds or more. To prevent the connection from being dropped, initiate more traffic over the connection or enable TCP keepalive on the instance with a value of less than 350 seconds.
NAT gateways currently do not support the IPsec protocol.
NAT gateways support traffic with a maximum transmission unit (MTU) of 8500 bytes.
Each IPv4 address can support up to 55,000 simultaneous connections to each unique destination. You can increase this limit by associating up to 8 IPv4 addresses to your NAT gateways (1 primary IPv4 address and 7 secondary IPv4 addresses). By default, you can associate up to 2 Elastic IP addresses per public NAT gateway (quota increase available).
NAT Gateway Types
Public NAT Gateway
Enables instances in private subnets to connect to the internet
Requires an Elastic IP address
Must be created in a public subnet (for zonal mode)
Supports up to 8 IPv4 addresses (1 primary + 7 secondary)
Private NAT Gateway
Enables instances in private subnets to connect to other VPCs or on-premises networks via Transit Gateway or virtual private gateway
Does not require an Elastic IP address
Uses private IP address for source NAT
Cannot be used for internet connectivity
Useful for communication between VPCs with overlapping CIDR ranges
Regional NAT Gateway (Announced November 2025)
A regional NAT gateway automatically expands across Availability Zones based on workload presence, unlike standard zonal NAT gateways which operate in a single AZ.
Does not require a public subnet – creates its own route table with a pre-configured route to the internet gateway.
Provides automatic high availability without manual multi-AZ configuration.
Simplifies setup – no need to create/delete NAT Gateways or edit route tables when workloads expand to new AZs.
Supports up to 32 IP addresses per Availability Zone (compared to 8 for zonal NAT gateways).
May take up to 60 minutes to expand to a new AZ after a resource is launched there.
Supports two modes:
Automatic mode – AWS manages IP addresses and AZ expansion (recommended)
Manual mode – You manually manage IP addresses and control AZ expansion/contraction
Supports AWS Transit Gateway as a valid route in the regional NAT gateway route table.
Does not support private NAT connectivity (use zonal NAT gateways for private NAT use cases).
Available in all commercial AWS Regions (except AWS GovCloud and China Regions).
Regional NAT Gateway vs Zonal NAT Gateway
Zonal NAT Gateway (Traditional)
Created in a specific Availability Zone
Requires a public subnet in each AZ for high availability
Requires manual creation of NAT Gateway in each AZ
Requires route table updates for each AZ
Supports up to 8 IP addresses
Supports both public and private connectivity types
Best for: Predictable, static workloads; private NAT use cases
Regional NAT Gateway
Automatically spans all AZs based on workload presence
No public subnet required
Single NAT Gateway resource to manage
Automatic routing across AZs
Supports up to 32 IP addresses per AZ
Public connectivity only (no private NAT support)
Best for: Dynamic workloads that scale across AZs, simplified management, new deployments
NAT Instance
⚠️ NAT Instance – Legacy (Not Recommended)
The NAT AMI is built on the last version of Amazon Linux AMI, 2018.03, which reached end of standard support on December 31, 2020 and end of maintenance support on December 31, 2023.
AWS recommends migrating to a NAT Gateway for better availability, higher bandwidth, and less administrative effort.
If NAT instances are required for your use case (e.g., cost optimization for non-production environments), you can create your own NAT AMI from a current version of Amazon Linux.
NAT Gateway vs NAT Instance
AWS Certification Exam Practice Questions
Questions are collected from Internet and the answers are marked as per my knowledge and understanding (which might differ with yours).
AWS services are updated everyday and both the answers and questions might be outdated soon, so research accordingly.
AWS exam questions are not updated to keep up the pace with AWS updates, so even if the underlying feature has changed the question might not be updated
Open to further feedback, discussion and correction.
After launching an instance that you intend to serve as a NAT (Network Address Translation) device in a public subnet you modify your route tables to have the NAT device be the target of internet bound traffic of your private subnet. When you try and make an outbound connection to the Internet from an instance in the private subnet, you are not successful. Which of the following steps could resolve the issue?
Attaching a second Elastic Network interface (ENI) to the NAT instance, and placing it in the private subnet
Attaching an Elastic IP address to the instance in the private subnet
Attaching a second Elastic Network Interface (ENI) to the instance in the private subnet, and placing it in the public subnet
Disabling the Source/Destination Check attribute on the NAT instance
You manually launch a NAT AMI in a public subnet. The network is properly configured. Security groups and network access control lists are property configured. Instances in a private subnet can access the NAT. The NAT can access the Internet. However, private instances cannot access the Internet. What additional step is required to allow access from the private instances?
Enable Source/Destination Check on the private Instances.
Enable Source/Destination Check on the NAT instance.
Disable Source/Destination Check on the private instances
Disable Source/Destination Check on the NAT instance
A user has created a VPC with public and private subnets. The VPC has CIDR 20.0.0.0/16. The private subnet uses CIDR 20.0.1.0/24 and the public subnet uses CIDR 20.0.0.0/24. The user is planning to host a web server in the public subnet (port 80. and a DB server in the private subnet (port 3306.. The user is configuring a security group of the NAT instance. Which of the below mentioned entries is not required for the NAT security group?
For Inbound allow Source: 20.0.1.0/24 on port 80
For Outbound allow Destination: 0.0.0.0/0 on port 80
For Outbound allow Destination: 0.0.0.0/0 on port 443
A web company is looking to implement an external payment service into their highly available application deployed in a VPC. Their application EC2 instances are behind a public facing ELB. Auto scaling is used to add additional instances as traffic increases. Under normal load the application runs 2 instances in the Auto Scaling group but at peak it can scale 3x in size. The application instances need to communicate with the payment service over the Internet, which requires whitelisting of all public IP addresses used to communicate with it. A maximum of 4 whitelisting IP addresses are allowed at a time and can be added through an API. How should they architect their solution?
Route payment requests through two NAT instances setup for High Availability and whitelist the Elastic IP addresses attached to the NAT instances
Whitelist the VPC Internet Gateway Public IP and route payment requests through the Internet Gateway. (Internet gateway is only to route traffic)
Whitelist the ELB IP addresses and route payment requests from the Application servers through the ELB. (ELB does not have a fixed IP address)
Automatically assign public IP addresses to the application instances in the Auto Scaling group and run a script on boot that adds each instances public IP address to the payment validation whitelist API. (would exceed the allowed 4 IP addresses)
A company needs to provide internet access to instances in private subnets across multiple Availability Zones with automatic high availability and simplified management. Which NAT Gateway option should they use?
Create a public NAT Gateway in each Availability Zone
Create a Regional NAT Gateway that automatically spans all Availability Zones
Create a private NAT Gateway in each Availability Zone
Use NAT instances with Auto Scaling
An organization has two VPCs with overlapping CIDR ranges that need to communicate with each other through a Transit Gateway. Which NAT Gateway type should be used to enable this communication?
Public NAT Gateway with Elastic IP addresses
Regional NAT Gateway in automatic mode
Private NAT Gateway connected to a Transit Gateway
NAT Instance with Source/Destination Check disabled
A company’s NAT Gateway is experiencing port exhaustion when communicating with a popular third-party API endpoint. What is the most effective solution to increase the number of simultaneous connections?
Create multiple NAT Gateways in the same subnet
Associate secondary IPv4 addresses with the NAT Gateway to increase the connection limit
Increase the NAT Gateway bandwidth allocation
Replace the NAT Gateway with a NAT Instance using a larger instance type
Virtual Private Cloud (VPC) provides networking functionality to Compute Engine virtual machine (VM) instances, Google Kubernetes Engine (GKE) clusters, and serverless workloads. VPC provides networking for the cloud-based resources and services that is global, scalable, and flexible.
VPC Networks
VPC network is a virtual version of a physical network, implemented inside of Google’s production network by using Andromeda (Google’s distributed network virtualization platform).
A VPC network is a global resource that consists of a list of regional virtual subnets in data centers, all connected by a global wide area network.
VPC networks are logically isolated from each other in Google Cloud.
VPC networks
provides connectivity for the Compute Engine VMs, including GKE clusters, serverless workloads, and other Google Cloud products built on Compute Engine VMs
offers built-in internal passthrough Network Load Balancers and proxy systems for internal Application Load Balancers.
connects to on-premises networks using Cloud VPN tunnels and VLAN attachments for Cloud Interconnect.
distributes traffic from Google Cloud external load balancers to backends
Specifications
VPC networks are global resources, including the associated routes and firewall rules, and are not associated with any particular region or zone.
Subnets are regional resources and each subnet defines a range of IP addresses.
Firewall rules control the traffic to and from instances. Rules are implemented on the VMs themselves, so traffic can only be controlled and logged as it leaves or arrives at a VM.
Resources within a VPC network can communicate with one another by using internal IPv4 addresses (and IPv6 addresses in dual-stack or IPv6-only subnets), subject to applicable network firewall rules.
Private access options for services allow instances with internal IP addresses to communicate with Google APIs and services.
Network administration can be secured by using IAM roles.
An organization can use Shared VPC to keep a VPC network in a common host project. Authorized IAM members from other projects in the same organization can create resources that use Shared VPC network subnets.
VPC Network Peering allows VPC networks to be connected with other VPC networks in different projects or organizations.
VPC networks can be securely connected in hybrid environments by using Cloud VPN or Cloud Interconnect.
VPC networks support IPv4 unicast traffic, and now also support IPv6 traffic through dual-stack and IPv6-only subnets (available in custom-mode VPC networks only). Broadcast and multicast traffic are not supported within the network.
Network Connectivity Center (NCC) can be used to connect VPC networks via a hub-and-spoke model using VPC spokes, supporting up to 250 VPC spokes per hub.
VPC Subnets
VPC networks do not have any IP address ranges associated with them.
Each VPC network consists of one or more useful IP range partitions called subnets and IP ranges are defined for the subnets.
Subnets are regional resources and each subnet is associated with a region.
A network must have at least one subnet before it can be used.
More than one subnet per region can be created.
VPC Network supports the following subnet creation mode
Auto mode VPC networks
create subnets in each region automatically
adds new subnets automatically, if a new region becomes available
can be switched to custom mode VPC networks
support only IPv4 subnet ranges
Custom mode VPC networks
start with no subnets, giving full control over subnet creation.
are more flexible and are better suited for production
cannot be switched to auto mode VPC networks
support IPv4, dual-stack (IPv4 + IPv6), and IPv6-only subnet configurations
Subnet must have a defined primary IP address range, and any resources created within are assigned an IP address from the defined range.
Subnets can be assigned a secondary IP address range, which is only used by alias IP ranges. This is useful if you have multiple services running on a VM and want to assign each service a different IP address.
Primary IP range of an existing subnet can be expanded by modifying its subnet mask, setting the prefix length to a smaller number.
Dual-stack (IPv4 and IPv6) subnets — have both IPv4 and IPv6 address ranges. The IPv6 subnet range is /64 (e.g., fd20:a:b:c::/64).
IPv6 can be either internal ULA (Unique Local Address) or external GUA (Globally Unique Address)
Internal ULA requires the VPC network internal IPv6 range to be enabled
IPv6-only subnets — support only IPv6 addressing. Can use DNS64 and NAT64 to access IPv4-only destinations.
IPv6 functionality is available only in Premium Tier networking.
IPv6 addressing is not available in auto mode VPC networks — only custom mode networks support IPv6.
VPC Routes
Routes define paths for packets leaving instances (egress traffic), either inside the network or outside of Google Cloud.
A route consists of
a single destination prefix in CIDR format (0.0.0.0/0) and
a single next hop (for e.g. Internet Gateway)
When an instance in a VPC network sends a packet, Google Cloud delivers the packet to the route’s next hop if the packet’s destination address is within the route’s destination range.
Routes are defined at the VPC network level but implemented at each VM instance level.
Each VM instance has a controller that is kept informed of all applicable routes from the network’s routing table. Each packet leaving a VM is delivered to the appropriate next hop of an applicable route based on a routing order. When a route is added or deleted, the set of changes is propagated to the VM controllers by using an eventually consistent design.
Routes are divided into two categories: system-generated and custom.
system-generated routes
default — send traffic from eligible instances to the internet and can be removed or replaced
subnet routes — route traffic among its subnets and updated automatically by Google Cloud
are applied at the VPC level to all the instances
custom routes
are either static routes created manually or dynamic routes maintained automatically by one or more of the Cloud Routers
can be applied to all the instances or specific instance using network tag
Policy-based routes let you direct traffic based on more than just the destination IP address — they can match on source IP, protocol, and port to steer traffic to specific next hops (e.g., for third-party network appliances).
A migration tool is available to convert existing VPC firewall rules to global network firewall policies.
VPC Private Access Options
Google Cloud provides several private access options which allow VM instances with internal IP addresses to reach certain APIs and services.
Private Google Access
allows VMs to connect to the set of external IP addresses used by Google APIs and services by enabling Private Google Access on the subnet used by the VM’s network interface.
allows access to the external IP addresses used by App Engine, including third-party App Engine-based services.
configured on a subnet by subnet basis
provides following routing options
use default route with its next-hop being the default internet gateway, and it provides a path to the default domains, private.googleapis.com, and restricted.googleapis.com.
use custom static routes, each having a more specific destination, and each using the default internet gateway next hop.
Use this option to connect to Google APIs and services without giving the Google Cloud resources external IP addresses.
Private Service Connect (PSC)
is a capability of Google Cloud networking that allows consumers to access managed services privately from inside their VPC network.
allows managed service producers to host services in their own separate VPC networks and offer a private connection to their consumers.
creates a private endpoint with an internal IP address in the consumer’s VPC to access producer services.
supports access to Google APIs (global and regional), published third-party services, and your own services.
PSC Endpoints — consumer-side resources for accessing published services or Google APIs via an internal IP.
PSC Interfaces — allow producer VPCs to initiate connections to consumer VPCs via network attachments.
Service Connectivity Automation — lets service consumers automate the deployment of connectivity to managed services using service connection policies.
PSC is the recommended approach for private connectivity to Google Cloud managed services.
Private services access
is a private connection between the VPC network and a network owned by Google or a third party i.e. service producers
enables VM instances in the VPC network and the accessed services to communicate exclusively by using internal IP addresses.
VM instances don’t need Internet access or external IP addresses to reach services that are available through private services access.
Use this option to connect to specific Google and third-party services without assigning external IP addresses to the Google Cloud and Google or third-party resources.
Network Connectivity Center (NCC) provides a hub-and-spoke connectivity model for connecting VPC networks.
VPC spokes let you connect two or more VPC networks to an NCC hub so that the networks can exchange subnet routes.
Supports up to 250 VPC spokes per hub and millions of VMs.
Provides smooth workload mobility between VPCs and simplified management of cross-VPC connectivity.
Also supports hybrid spokes (Cloud VPN, Cloud Interconnect, Router Appliance) for connecting on-premises/multi-cloud networks.
NCC is an alternative to VPC Peering for large-scale network topologies, providing centralized management and transitive connectivity.
VPC Flow Logs
VPC Flow Logs records a sample of network flows sent from and received by VM instances, including instances used as GKE nodes.
Flow Logs can be used for network monitoring, forensics, real-time security analysis, and expense optimization.
Flow logs can be configured at multiple levels:
Organization level — enables flow logs for all subnets, VLAN attachments, and Cloud VPN tunnels across the entire organization
VPC network level — enables for all subnets in a VPC
Subnet level — enables for a specific subnet
VLAN attachment level — for Cloud Interconnect traffic
Cloud VPN tunnel level — for VPN traffic
Flow logs record TCP, UDP, ICMP, ESP, and GRE connections.
With GCP Shared VPC, all Flow logs are in the host project.
Cloud Logging can be used to view the flow logs and it can be exported to any destination that Cloud Logging export supports.
Flow logs are aggregated by the connection from Compute Engine VMs and exported in real-time.
Flow logs can be analyzed using real-time streaming APIs by subscribing to Pub/Sub.
Flow logs are collected for each VM connection at specific intervals (sampling period). All packets collected for a given interval for a given connection are aggregated for a period of time (aggregation interval) into a single flow log entry.
VPC Flow Logs for Cross-Cloud Network — expanded support for logging traffic across multi-cloud and hybrid topologies.
Organization policy constraints can be configured to enforce VPC Flow Logs enablement.
Hybrid Subnets (Preview)
Hybrid Subnets helps migrate workloads to Google Cloud without needing to change any IP addresses.
A hybrid subnet is a single logical subnet that combines a segment of an on-premises network with a subnet in a VPC network.
Enables gradual migration where workloads can reside both on-premises and in Google Cloud on the same subnet during transition.
Useful for lift-and-shift migrations where changing IP addresses is impractical.
GCP Certification Exam Practice Questions
Questions are collected from Internet and the answers are marked as per my knowledge and understanding (which might differ with yours).
GCP services are updated everyday and both the answers and questions might be outdated soon, so research accordingly.
GCP exam questions are not updated to keep up the pace with GCP updates, so even if the underlying feature has changed the question might not be updated
Open to further feedback, discussion and correction.
Your VMs are running in a subnet that has a subnet mask of 255.255.255.240. The current subnet has no more free IP addresses and you require an additional 10 IP addresses for new VMs. The existing and new VMs should all be able to reach each other without additional routes. What should you do?
Use gcloud to expand the IP range of the current subnet.
Delete the subnet, and recreate it using a wider range of IP addresses.
Create a new project. Use Shared VPC to share the current network with the new project.
Create a new subnet with the same starting IP but a wider range to overwrite the current subnet
An IT company has a set of compute engine instances hosted in a VPC. They are not exposed to the internet. These instances now need to install an important security patch. How can the security patch be installed on the instances?
Upload to Cloud Storage and enable VPC peering
Upload to Cloud Storage and whitelist instance IP address
Upload to Cloud Storage and enable Private Google Access
Upload to Cloud Source Repository and enable VPC peering
Your security team wants to be able to audit network traffic inside of your network. What’s the best way to ensure they have access to the data they need?
Disable flow logs.
Enable flow logs.
Enable VPC Network logs
Add a firewall capture filter.
Your organization needs to provide private connectivity from a VPC to a managed Google service without using external IP addresses. The solution should assign an internal IP address for the connection. What should you use?
VPC Network Peering
Private Google Access
Private Service Connect
Cloud VPN
You need to connect 50 VPC networks across different projects in your organization with centralized management and transitive routing. Which solution is most appropriate?
Create VPC Peering between all networks
Use Shared VPC for all projects
Use Network Connectivity Center with VPC spokes
Create Cloud VPN tunnels between all networks
You are deploying IPv6 workloads in Google Cloud. Which VPC network mode supports dual-stack subnets?
Auto mode VPC networks
Custom mode VPC networks
Both auto mode and custom mode
Legacy networks
Your organization wants to enforce consistent firewall rules across multiple VPC networks in different projects and folders. What should you use?
is a horizontally scaled, redundant, and highly available component that allows communication between instances in your VPC and the internet.
imposes no availability risks or bandwidth constraints on your network traffic.
serves two purposes: to provide a target in the VPC route tables for internet-routable traffic and to perform NAT for instances that have not been assigned public IPv4 addresses.
enables instances in a private subnet to connect to the internet or other AWS services, but prevents the Internet from initiating connections with the instances.
Public NAT gateway allows instances in private subnets to connect to the internet through the NAT gateway’s Elastic IP address.
Private NAT gateway allows instances in private subnets to connect to other VPCs or the on-premises network using its private IP address for source NAT.
Regional NAT Gateway (New – Nov 2025) – automatically expands across Availability Zones based on workload presence. Unlike standard (zonal) NAT gateways which operate in a single AZ, regional NAT gateways follow workloads to provide automatic high availability without requiring a public subnet to host the gateway.
Egress Only Internet Gateway
NAT devices are not supported for IPv6 traffic, use an Egress-only Internet gateway instead
Egress-only Internet gateway is a horizontally scaled, redundant, and highly available VPC component
Egress-only Internet gateway allows outbound communication over IPv6 from instances in the VPC to the Internet and prevents the Internet from initiating an IPv6 connection with your instances.
VPC endpoint provides a private connection from VPC to supported AWS services and VPC endpoint services powered by PrivateLink without requiring an internet gateway, NAT device, VPN connection, or AWS Direct Connect connection.
Instances in the VPC do not require public IP addresses to communicate with resources in the service. Traffic between the VPC and the other service does not leave the Amazon network.
VPC Endpoints are virtual devices and are horizontally scaled, redundant, and highly available VPC components that allow communication between instances in the VPC and services without imposing availability risks or bandwidth constraints on the network traffic.
VPC Endpoints are of three types
Interface Endpoints – is an elastic network interface with a private IP address that serves as an entry point for traffic destined to supported services.
Gateway Endpoints – is a gateway that is a target for a specified route in your route table, used for traffic destined to a supported AWS service. Currently only Amazon S3 and DynamoDB.
Resource Endpoints (New – Dec 2024) – enables private access to a specific resource (e.g., RDS database, IP address, or domain name) in another VPC or on-premises environment shared via AWS RAM, without requiring an NLB.
Cross-Region PrivateLink (Nov 2025) – Interface VPC endpoints now support cross-region connectivity, breaking the previous limitation that endpoints were regional-only. This enables connecting to VPC endpoint services hosted in other AWS Regions within the same partition.
provides private connectivity between VPCs, AWS services, and your on-premises networks without exposing your traffic to the public internet.
helps privately expose a service/application residing in one VPC (service provider) to other VPCs (consumer) within an AWS Region in a way that only consumer VPCs initiate connections to the service provider VPC.
With ALB as a target of NLB, ALB’s advanced routing capabilities can be combined with AWS PrivateLink.
VPC Resource Gateway (Dec 2024) – allows sharing any VPC resource (RDS databases, domain names, IP addresses) via AWS RAM. Consumers access these resources privately using VPC endpoints without needing an NLB, simplifying hybrid networking.
Cross-Region Connectivity (Nov 2025) – PrivateLink now supports native cross-region access for both AWS services and customer endpoint services, enabling global private connectivity from a single Region deployment.
enables networking connection between two VPCs to route traffic between them using private IPv4 addresses or IPv6 addresses
connections can be created between your own VPCs, or with a VPC in another AWS account.
enables full bidirectional connectivity between the VPCs
supports inter-region VPC peering connection
Inter-region peering now supports jumbo frames (up to 8500 bytes MTU) and full instance bandwidth (Mar 2025)
uses existing underlying AWS infrastructure
does not have a single point of failure for communication or a bandwidth bottleneck.
VPC Peering connections have limitations
cannot be used with Overlapping CIDR blocks
does not provide Transitive peering
does not support Edge to Edge routing through Gateway or private connection
is best used when resources in one VPC must communicate with resources in another VPC, the environment of both VPCs is controlled and secured, and the number of VPCs to be connected is less than 10
supports a limit of 125 active peering connections per VPC
Simplified Billing (Apr 2025) – AWS simplified VPC Peering billing; no changes to data transfer pricing but billing structure is streamlined.
VPN CloudHub
AWS VPN CloudHub allows you to securely communicate from one site to another using AWS Managed VPN or Direct Connect
AWS VPN CloudHub operates on a simple hub-and-spoke model that can be used with or without a VPC
AWS VPN CloudHub can be used if you have multiple branch offices and existing internet connections and would like to implement a convenient, potentially low cost hub-and-spoke model for primary or backup connectivity between these remote offices.
AWS VPN CloudHub leverages VPC virtual private gateway with multiple gateways, each using unique BGP autonomous system numbers (ASNs).
⚠️ Note: Transit VPC is a legacy architecture pattern. AWS recommends using AWS Transit Gateway or AWS Cloud WAN for new deployments, which provide managed, highly available hub-and-spoke connectivity without the operational overhead of managing EC2-based virtual appliances.
A transit VPC is a common strategy for connecting multiple, geographically disperse VPCs and remote networks in order to create a global network transit center.
A transit VPC simplifies network management and minimizes the number of connections required to connect multiple VPCs and remote networks
Transit VPC can be used to support important use cases
Private Networking – You can build a private network that spans two or more AWS Regions.
Shared Connectivity – Multiple VPCs can share connections to data centers, partner networks, and other clouds.
Cross-Account AWS Usage – The VPCs and the AWS resources within them can reside in multiple AWS accounts.
Transit VPC design helps implement more complex routing rules, such as network address translation between overlapping network ranges, or to add additional network-level packet filtering or inspection.
Transit VPC
supports Transitive routing using the overlay VPN network — allowing for a simpler hub and spoke design.
supports network address translation between overlapping network ranges.
supports vendor functionality around advanced security (layer 7 firewall/IPS/IDS) using third-party software on EC2
leverages instance-based routing that increases costs while lowering availability and limiting the bandwidth.
Customers are responsible for managing the HA and redundancy of EC2 instances running the third-party vendor virtual appliance
is a highly available and scalable service to consolidate the AWS VPC routing configuration for a region with a hub-and-spoke architecture.
is a Regional resource and can connect thousands of VPCs within the same AWS Region.
TGWs across different regions can peer with each other to enable VPC communications within the same or different regions.
provides simpler VPC-to-VPC communication management over VPC Peering with a large number of VPCs.
enables you to attach VPCs (across accounts) and VPN connections in the same Region and route traffic between them.
support dynamic and static routing between attached VPCs and VPN connections
removes the need for using full mesh VPC Peering and Transit VPC
Transit Gateway Flow Logs – enables capturing detailed telemetry (source/destination IPs, ports, protocol, traffic counters, timestamps) for all network flows traversing the Transit Gateway. Logs can be published to CloudWatch Logs, S3, or Firehose.
Flexible Cost Allocation (Nov 2025) – provides granular control over how Transit Gateway data processing costs are allocated across AWS accounts within AWS Organizations.
AWS Cloud WAN
is a managed wide area networking (WAN) service that helps build, manage, and monitor a unified global network connecting cloud and on-premises resources.
provides a central dashboard and network policies to create a global network spanning multiple locations, removing the need to configure and manage different networks using different technologies.
uses a policy-based automation system to define network segments, attach VPCs, VPN connections, and SD-WAN products.
simplifies global network management compared to manually managing Transit Gateways across regions.
key features include:
Central Dashboard – manage branch offices, data centers, VPN connections, SD-WAN, VPCs, and Transit Gateways from one place.
Network Policies – define how traffic is routed between segments with policy-based controls.
Service Insertion (2024) – streamlines integrating security and inspection services (e.g., Network Firewall) into global networks.
Routing Policy (Nov 2025) – enables route filtering, summarization, and BGP path manipulation for fine-grained traffic control at scale.
Security Group Referencing & Enhanced DNS (Jun 2025) – simplifies security group management and DNS resolution across Cloud WAN segments.
can be used as a migration path from Transit Gateway for organizations needing global, multi-Region network management.
available in AWS GovCloud (US) Regions as of Jun 2026.
VPC provides the option of creating an IPsec VPN connection between remote customer networks and their VPC over the internet
AWS managed VPN endpoint includes automated multi–data center redundancy & failover built into the AWS side of the VPN connection
AWS managed VPN consists of two parts
Virtual Private Gateway (VPG) on AWS side
Customer Gateway (CGW) on the on-premises data center
AWS Site-to-Site VPN only provides Site-to-Site VPN connectivity. It does not provide Point-to-Site VPC connectivity (use AWS Client VPN for that).
Virtual Private Gateway are Highly Available as it represents two distinct VPN endpoints, physically located in separate data centers to increase the availability of the VPN connection.
High Availability on the on-premises data center must be handled by creating additional Customer Gateway.
AWS Site-to-Site VPN connections are low cost, quick to setup and start with compared to Direct Connect. However, they are not reliable as they traverse through Internet.
5 Gbps Bandwidth Tunnels (Nov 2025) – supports VPN connections with up to 5 Gbps bandwidth per tunnel, a 4x improvement from the previous 1.25 Gbps limit. Beneficial for bandwidth-intensive hybrid applications, big data migrations, and disaster recovery. Bandwidth can be modified on existing connections without changing on-premises configuration (May 2026).
IPv6 Support for Outer Tunnel IPs (Jul 2025) – supports IPv6 addresses on outer tunnel IPs, enabling full IPv6-only VPN connectivity (IPv6-in-IPv6) and mixed (IPv4-in-IPv6) configurations without IPv6>IPv4>IPv6 translation.
VPN Concentrator (Nov 2025) – a new feature that simplifies multi-site connectivity for distributed enterprises with 25+ remote sites needing low bandwidth (under 100 Mbps each). Connects multiple remote sites through a single VPN attachment to Transit Gateway with 5 Gbps aggregate bandwidth.
AWS Client VPN
is a fully managed, scalable VPN service that provides an endpoint for users to establish a secure remote access (Point-to-Site) connection to the AWS network.
uses OpenVPN-based VPN client software for secure connectivity.
handles Point-to-Site VPN connectivity that AWS Site-to-Site VPN does not provide (e.g., remote worker/mobile access).
supports authentication via Active Directory, SAML-based federated authentication, and mutual certificate authentication.
IPv6 Connectivity (Aug 2025) – now supports full IPv6 connectivity for Client VPN endpoints, allowing connections to IPv6 resources in VPCs and from clients on IPv6 networks.
Software VPN
VPC offers the flexibility to fully manage both sides of the VPC connectivity by creating a VPN connection between your remote network and a software VPN appliance running in your VPC network.
Software VPNs help manage both ends of the VPN connection either for compliance purposes or for leveraging gateway devices that are not currently supported by Amazon VPC’s VPN solution.
Software VPNs allows you to handle Point-to-Site connectivity (though AWS Client VPN is now the recommended managed alternative).
Software VPNs, with the above design, introduces a single point of failure and needs to be handled.
AWS Direct Connect helps establish a dedicated private connection between an on-premises network and AWS.
Direct Connect can reduce network costs, increase bandwidth throughput, and provide a more consistent network experience than internet-based or VPN connections
Direct Connect uses industry-standard VLANs to access EC2 instances running within a VPC using private IP addresses
Direct Connect lets you establish
Dedicated Connection: A 1G, 10G, or 100G physical Ethernet connection associated with a single customer through AWS.
Hosted Connection: A physical Ethernet connection that an AWS Direct Connect Partner provisions on behalf of a customer. Speeds range from 50 Mbps to 10 Gbps.
Direct Connect provides the following Virtual Interfaces
Private virtual interface – to access a VPC using private IP addresses.
Public virtual interface – to access all AWS public services using public IP addresses.
Transit virtual interface – to access one or more transit gateways associated with Direct Connect gateways.
Direct Connect connections are not redundant as each connection consists of a single dedicated connection between ports on your router and an Amazon router
Direct Connect High Availability can be configured using
Multiple Direct Connect connections
Back-up IPSec VPN connection
SiteLink – enables sending data between AWS Direct Connect locations to create private network connections between offices and data centers in a global network, bypassing AWS Regions. Data travels over the shortest path between locations using the AWS global network backbone.
VIF Rate Limiters (Jun 2026) – supports Virtual Interface Rate Limiters on dedicated connections to prevent network congestion caused by unexpected traffic spikes on a VIF, protecting other VIFs on the same connection.
LAGs
Direct Connect link aggregation group (LAG) is a logical interface that uses the Link Aggregation Control Protocol (LACP) to aggregate multiple connections at a single AWS Direct Connect endpoint, allowing you to treat them as a single, managed connection.
LAGs need the following
All connections in the LAG must use the same bandwidth.
A maximum of four connections in a LAG. Each connection in the LAG counts toward the overall connection limit for the Region.
All connections in the LAG must terminate at the same AWS Direct Connect endpoint.
offers a Free Tier – fully managed 500 Mbps interconnect to another CSP at no charge on the AWS side (May 2026).
eliminates complex multicloud networking setups that previously required physical Direct Connect connections and manual peering arrangements.
Amazon VPC Lattice
is an application networking service that consistently connects, monitors, and secures communications between services and resources across VPCs and accounts.
automatically manages network connectivity and application layer routing between services across different VPCs and AWS accounts.
abstracts IP address dependencies, allowing applications to communicate securely without direct network routing.
supports HTTP, HTTPS, gRPC, TLS, and TCP protocols.
key features include:
Service Networks – logical grouping of services with shared access and observability policies.
Service Network VPC Endpoints – allows VPCs to connect to service networks via VPC endpoints.
VPC Resources Support (re:Invent 2024) – enables connectivity to TCP resources such as databases, domain names, and IP addresses across VPCs and accounts.
Auth Policies – fine-grained access control using IAM-based policies at the service network and service level.
can replace complex Transit Gateway and PrivateLink configurations for service-to-service communication within a Region.
does not natively support cross-Region service access; requires a proxy solution for external Region connectivity.
Amazon VPC Route Server
is a new managed service (GA Apr 2025) that enables dynamic routing within Amazon VPC using Border Gateway Protocol (BGP).
allows deploying endpoints in a VPC and peering them with virtual appliances to advertise routes using BGP.
filters received routes using standard BGP attributes and propagates selected routes to specified VPC route tables.
dynamically updates VPC and internet gateway route tables with preferred IPv4 or IPv6 routes for routing fault tolerance.
eliminates the need for complex scripting or Lambda-based failover mechanisms for virtual appliance routing.
key use cases:
Automatic active/standby failover for inspection appliances
Dynamic routing between cloud applications and on-premises systems via virtual appliances
Integration with Transit Gateway for centralized inspection architectures
Logging Enhancements (Jun 2025) – provides real-time monitoring of BGP and BFD session states, historical peer-to-peer session data, with delivery via CloudWatch, S3, Data Firehose, or AWS CLI.
AWS VPC – Virtual Private Cloud is a virtual network dedicated to the AWS account. It is logically isolated from other virtual networks in the AWS cloud.
VPC allows the users complete control over their virtual networking environment, including the selection of their own IP address range, creation of subnets, and configuration of route tables and network gateways.
VPC allows you to use both IPv4 and IPv6 in your VPC for secure and easy access to resources and applications.
VPC is a regional service and it spans all of the AZs in the Region. Availability zones (AZ) are multiple, isolated locations within each Region.
VPC Sizing
VPC needs a set of IP addresses in the form of a Classless Inter-Domain Routing (CIDR) block for e.g, 10.0.0.0/16, which allows 2^16 (65536) IP address to be available
Allowed CIDR block size is between
/28 netmask (minimum with 2^4 – 16 available IP address) and
/16 netmask (maximum with 2^16 – 65536 IP address)
CIDR block from private (non-publicly routable) IP address can be assigned
10.0.0.0 – 10.255.255.255 (10/8 prefix)
172.16.0.0 – 172.31.255.255 (172.16/12 prefix)
192.168.0.0 – 192.168.255.255 (192.168/16 prefix)
It’s possible to specify a range of publicly routable IP addresses; however, direct access to the Internet is not currently supported from publicly routable CIDR blocks in a VPC
CIDR block once assigned to the VPC cannot be modified.NOTE – You can now resize VPC. Read AWS blog post.
Each VPC is separate from any other VPC created with the same CIDR block even if it resides within the same AWS account
Connection between your VPC and corporate or home network can be established, however, the CIDR blocks should be not be overlapping for e.g. VPC with CIDR 10.0.0.0/16 can communicate with 10.1.0.0/16 corporate network but the connections would be dropped if it tries to connect to 10.0.37.0/16 corporate network cause of overlapping IP addresses.
VPC allows you to set tenancy options for the Instances launched in it. By default, the tenancy option is shared. If the dedicated option is selected, all the instances within it are launched on dedicated hardware overriding the individual instance tenancy setting.
Deletion of the VPC is possible only after terminating all instances within the VPC and deleting all the components with the VPC e.g. subnets, security groups, network ACLs, route tables, Internet gateways, VPC peering connections, and DHCP options
VPC Peering provides a networking connection between two VPCs (same or different account and region) that enables routing of traffic between them using private IPv4 addresses or IPv6 addresses.
NAT Gateway enables instances in a private subnet to connect to the Internet but prevents the Internet from initiating connections with the instances.
VPC endpoints enable the creation of a private connection between VPC to supported AWS services and VPC endpoint services powered by PrivateLink using its private IP address.
Subnets
Subnet spans a single Availability Zone, distinct locations engineered to be isolated from failures in other AZs, and cannot span across AZs
Subnet can be configured with an Internet gateway to enable communication over the Internet, or virtual private gateway (VPN) connection to enable communication with your corporate network
Subnet can be Public or Private and it depends on whether it has Internet connectivity i.e. is able to route traffic to the Internet through the IGW
Instances within the Public Subnet should be assigned a Public IP or Elastic IP address to be able to communicate with the Internet
For Subnets not connected to the Internet, but has traffic routed through Virtual Private Gateway only is termed as VPN-only subnet
Subnets can be configured to Enable assignment of the Public IP address to all the Instances launched within the Subnet by default, which can be overridden during the creation of the Instance
Subnet Sizing
CIDR block assigned to the Subnet can be the same as the VPC CIDR, in this case you can launch only one subnet within your VPC
CIDR block assigned to the Subnet can be a subset of the VPC CIDR, which allows you to launch multiple subnets within the VPC
CIDR block assigned to the subnet should not be overlapping
CIDR block size allowed is between
/28 netmask (minimum with 2^4 – 16 available IP address) and
/16 netmask (maximum with 2^16 – 65536 IP address)
AWS reserves 5 IPs address (first 4 and last 1 IP address) in each Subnet which are not available for use and cannot be assigned to an instance. for e.g. for a Subnet with a CIDR block 10.0.0.0/24 the following five IPs are reserved
10.0.0.0: Network address
10.0.0.1: Reserved by AWS for the VPC router
10.0.0.2: Reserved by AWS for mapping to Amazon-provided DNS
10.0.0.3: Reserved by AWS for future use
10.0.0.255: Network broadcast address. AWS does not support broadcast in a VPC, therefore the address is reserved.
Subnet Routing
Each Subnet is associated with a route table that controls the traffic.
Subnet Security
Subnet security can be configured using Security groups and NACLs
Security groups work at the instance level, and NACLs work at the subnet level
VPC & Subnet Sizing
VPC supports IPv4 and IPv6 addressing and has different CIDR block size limits for each
IPv6 CIDR block can be optionally associated with the VPC
VPC IPv4 CIDR block cannot be modified once created i.e. cannot increase or decrease the size of an existing CIDR block.
However, secondary CIDR blocks can be associated with the VPC to extend the VPC
Limitations
allowed block size is between a /28 netmask and /16 netmask.
CIDR block must not overlap with any existing CIDR block that’s associated with the VPC.
CIDR block must not be the same or larger than the CIDR range of a route in any of the VPC route tables for e.g. for a CIDR block 10.0.0.0/24, can only associate smaller CIDR blocks like 10.0.0.0/25
IP Addresses
Instances launched in the VPC can have Private, Public, and Elastic IP addresses assigned to them and are properties of ENI (Network Interfaces)
Private IP Addresses
Private IP addresses are not reachable over the Internet, and can be used for communication only between the instances within the VPC
All instances are assigned a private IP address, within the IP address range of the subnet, to the default network interface
Primary IP address is associated with the network interface for its lifetime, even when the instance is stopped and restarted and is released only when the instance is terminated
Additional Private IP addresses, known as secondary private IP address, can be assigned to the instances and these can be reassigned from one network interface to another
Public IP address
Public IP addresses are reachable over the Internet, and can be used for communication between instances and the Internet, or with other AWS services that have public endpoints
Public IP address assignment to the Instance depends if the Public IP Addressing is enabled for the Subnet.
Public IP address can also be assigned to the Instance by enabling the Public IP addressing during the creation of the instance, which overrides the subnet’s public IP addressing attribute
Public IP address is assigned from AWS pool of IP addresses and it is not associated with the AWS account and hence is released when the instance is stopped and restarted or terminated.
Elastic IP address
Elastic IP addresses are static, persistent public IP addresses that can be associated and disassociated with the instance, as required
Elastic IP address is allocated to the VPC and owned by the account unless released.
A Network Interface can be assigned either a Public IP or an Elastic IP. If you assign an instance, that already has a Public IP, an Elastic IP, the public IP is released
Elastic IP addresses can be moved from one instance to another, which can be within the same or different VPC within the same account
Elastic IPs are charged for non-usage i.e. if it is not associated or associated with a stopped instance or an unattached Network Interface
Elastic Network Interface (ENI)
Each Instance is attached to a default elastic network interface (Primary Network Interface eth0) and cannot be detached from the instance
ENI can include the following attributes
Primary private IP address
One or more secondary private IP addresses
One Elastic IP address per private IP address
One public IP address, which can be auto-assigned to the network interface for eth0 when you launch an instance, but only when you create a network interface for eth0 instead of using an existing ENI
One or more security groups
A MAC address
A source/destination check flag
A description
ENI’s attributes follow the ENI as it is attached or detached from an instance and reattached to another instance. When an ENI is moved from one instance to another, network traffic is redirected to the new instance.
Multiple ENIs can be attached to an instance and is useful for use cases:
Create a management network.
Use network and security appliances in your VPC.
Create dual-homed instances with workloads/roles on distinct subnets.
Create a low-budget, high-availability solution.
Route Tables
Route table defines rules, termed as routes, which determine where network traffic from the subnet would be routed
Each VPC has an implicit router to route network traffic
Each VPC has a Main Route table and can have multiple custom route tables created
Each Subnet within a VPC must be associated with a single route table at a time, while a route table can have multiple subnets associated with it
Subnet, if not explicitly associated to a route table, is implicitly associated with the main route table
Every route table contains a local route that enables communication within a VPC which cannot be modified or deleted
Route priority is decided by matching the most specific route in the route table that matches the traffic
Route tables need to be updated to define routes for Internet gateways, Virtual Private gateways, VPC Peering, VPC Endpoints, NAT Devices, etc.
VPC Route Server
Amazon VPC Route Server enables dynamic routing within a VPC using Border Gateway Protocol (BGP), simplifying routing between virtual appliances and cloud workloads.
VPC Route Server was announced GA in April 2025 and expanded to additional regions in January 2026.
Key Capabilities
Deploy Route Server endpoints in VPC and peer with virtual appliances using BGP
Dynamically updates VPC and internet gateway route tables with preferred IPv4 or IPv6 routes
Achieves routing fault tolerance for workloads running in subnets
Automatically reroutes traffic within a VPC for active/standby failover without static routes or manual intervention
Standard BGP attributes used for route filtering and selection
Use Cases
Network appliance high availability (automatic failover via BGP)
Centralized inspection with Transit Gateway for active/standby architectures
Third-party firewall and SD-WAN appliance integration
VPC Route Server eliminates the need for complex scripting or third-party solutions to handle dynamic routing and failover scenarios within a VPC.
Internet Gateways – IGW
An Internet gateway is a horizontally scaled, redundant, and highly available VPC component that allows communication between instances in the VPC and the Internet.
IGW imposes no availability risks or bandwidth constraints on the network traffic.
An Internet gateway serves two purposes:
To provide a target in the VPC route tables for Internet-routable traffic,
To perform network address translation (NAT) for instances that have been NOT been assigned public IP addresses.
Enabling Internet access to an Instance requires
Attaching Internet gateway to the VPC
Subnet should have route tables associated with the route pointing to the Internet gateway
Instances should have a Public IP or Elastic IP address assigned
Security groups and NACLs associated with the Instance should allow relevant traffic
NAT device enables instances in a private subnet to connect to the Internet or other AWS services, but prevents the Internet from initiating connections with the instances.
NAT devices do not support IPv6 traffic, use an egress-only Internet gateway instead.
Egress-only Internet gateway works as a NAT gateway, but for IPv6 traffic
Egress-only Internet gateway is a horizontally scaled, redundant, and highly available VPC component that allows outbound communication over IPv6 from instances in the VPC to the Internet, and prevents the Internet from initiating an IPv6 connection with the instances.
An egress-only Internet gateway is for use with IPv6 traffic only. To enable outbound-only Internet communication over IPv4, use a NAT gateway instead.
Shared VPCs
VPC sharing allows multiple AWS accounts to create their application resources, such as EC2 instances, RDS databases, Redshift clusters, and AWS Lambda functions, into shared, centrally-managed VPCs.
In this model, the account that owns the VPC (owner) shares one or more subnets with other accounts (participants) that belong to the same organization from AWS Organizations.
After a subnet is shared, the participants can view, create, modify, and delete their application resources in the subnets shared with them. Participants cannot view, modify, or delete resources that belong to other participants or the VPC owner.
VPC endpoint enables the creation of a private connection between VPC to supported AWS services and VPC endpoint services powered by PrivateLink using its private IP address
Traffic between VPC and AWS service does not leave the Amazon network
Endpoints are virtual devices, that are horizontally scaled, redundant, and highly available VPC components that allow communication between instances in the VPC and AWS services without imposing availability risks or bandwidth constraints on your network traffic.
Endpoints currently do not support cross-region requests, ensure that the endpoint is created in the same region as the S3 bucket
AWS currently supports the following types of Endpoints
A VPC peering connection is a networking connection between two VPCs that enables the routing of traffic between them using private IPv4 addresses or IPv6 addresses.
VPC peering connection is a one-to-one relationship between two VPCs and can be established between your own VPCs, or with a VPC in another AWS account in the same or different region.
VPC peering helps instances in either VPC can communicate with each other as if they are within the same network using AWS’s existing infrastructure of a VPC to create a peering connection; it is neither a gateway nor a VPN connection and does not rely on a separate piece of physical hardware.
VPC peering does not have any separate charges. However, there are data transfer charges.
VPC Flow Logs help capture information about the IP traffic going to and from network interfaces in the VPC and can help in monitoring the traffic or troubleshooting any connectivity issues.
Flow log can be created for the entire VPC, subnets, or each network interface. If enabled, for the entire VPC or subnet all the network interfaces within that resource are monitored.
Flow log can be configured to capture the type of traffic (accepted traffic, rejected traffic, or all traffic).
Flow logs do not capture real-time log streams for network interfaces.
Flow log data is collected outside of the path of the network traffic, and therefore does not affect network throughput or latency.
Flow logs can be created for network interfaces that are created by other AWS services; for e.g., ELB, RDS, ElastiCache, Redshift, and WorkSpaces.
Flow logs do not capture the following traffic
Traffic generated by instances when they contact the Amazon DNS server.
Traffic generated by a Windows instance for Amazon Windows license activation.
Traffic to and from 169.254.169.254 for instance metadata
Traffic to and from 169.254.169.123 for the Amazon Time Sync Service.
DHCP traffic.
Mirrored traffic.
Traffic to the reserved IP address for the default VPC router.
Traffic between an endpoint network interface and a Network Load Balancer network interface.
Troubleshooting traffic flow
If ACCEPT followed by REJECT, inbound was accepted by Security Groups and ACLs. However, rejected by NACLs outbound
If REJECT, inbound was either rejected by Security Groups OR NACLs.
VPC Block Public Access (BPA)
Amazon VPC Block Public Access (BPA) is a simple, declarative control that authoritatively blocks incoming (ingress) and outgoing (egress) VPC traffic through AWS-provided internet paths (launched November 2024).
VPC BPA supersedes any existing VPC settings (route tables, security groups, NACLs) to drop all traffic that would otherwise be exposed to the internet through Internet Gateways (IGW) or Egress-Only Internet Gateways (EIGW).
Key Features
Single declarative control to block internet access to/from VPCs and subnets
Can be set to bidirectional block (blocks all ingress and egress) or ingress-only block
Prevents accidental public exposure regardless of routing and security configuration
Supports subnet-level exclusions for DMZ architectures
Centralized enforcement across an AWS Organization
Deployment
Can be deployed across AWS Organizations using AWS CloudFormation or CLI
Supports IPv4 and IPv6 traffic blocking
Available in all commercial AWS regions and AWS China Regions (May 2025)
BPA is useful for accounts that should have no internet access (data processing, backend services) while allowing exceptions for specific subnets that require internet connectivity.
VPC Encryption Controls
VPC Encryption Controls is a security and compliance feature that provides centralized control to monitor and enforce encryption in transit for all traffic flows within and across VPCs in a region (GA 2025, paid feature from March 1, 2026).
VPC Encryption Controls uses both application-layer encryption and built-in encryption in transit capability of AWS Nitro System hardware to ensure encryption enforcement.
Operational Modes
Monitor mode – Audit the encryption status of traffic flows and identify resources allowing cleartext traffic
Enforce mode – Prevents creation or use of resources that allow unencrypted traffic; all traffic must be encrypted at hardware layer (Nitro) or application layer (TLS/SSL)
Key Capabilities
Centralized encryption policy enforcement across VPCs
Generates audit logs for compliance and reporting
Identifies resources that allow plaintext traffic
Works with Transit Gateway for inter-VPC encryption
Available in AWS GovCloud (US) Regions as of March 2026
Pricing
Fixed hourly rate for every non-empty VPC (with network interfaces) that has Encryption Controls enabled in either monitor or enforce mode
VPC Encryption Controls helps security teams demonstrate encryption compliance without relying on individual application teams to implement TLS correctly.
AWS VPC IP Address Manager (IPAM)
Amazon VPC IP Address Manager (IPAM) is a fully managed service that simplifies IP address management across AWS environments.
IPAM provides centralized visibility and control over IP address allocations across multiple AWS Regions and accounts within an AWS Organization.
Key benefits of IPAM:
Eliminates manual IP address tracking via spreadsheets or disparate systems
Automated IP address allocation and tracking
Prevents IP address conflicts and overlaps
Provides holistic view of IP address utilization
Supports both IPv4 and IPv6 address management
IPAM Features
Hierarchical pool structure for organizing IP address space
Automated CIDR allocation for VPCs and subnets
Cross-region and cross-account IP address visibility
Integration with AWS Organizations for centralized management
Compliance monitoring and reporting
IP address history and audit trails
IPAM Advanced Tier (launched 2025)
Infoblox infrastructure integration for hybrid cloud IP management
Manage AWS IP addresses through existing Infoblox workflows
Available for private scopes
Enhanced enterprise-grade capabilities
IPAM Integrations
Application Load Balancer (ALB) integration for predictable IP address blocks (March 2025)
IPAM Policies support for RDS and Application Load Balancers (January 2026)
Amazon CloudFront BYOIP for IPv6 through VPC IPAM integration (March 2026)
VPC CIDR allocation automation
AWS Resource Access Manager (RAM) for sharing IP pools
CloudWatch for monitoring and alerting
IPAM Pool Allocation Tags (May 2026)
Supports tags on IPAM pool allocations for organizing, governing, and controlling access to individual IP address allocations
Uses same tagging workflows as other AWS resources
Enables fine-grained access control via IAM policies based on allocation tags
IPAM helps network administrators organize, assign, monitor, and audit IP addresses at scale, reducing management burden and eliminating manual errors.
IPAM is available across all AWS commercial regions, including Asia Pacific (Taipei) as of June 2025.
Amazon VPC Lattice
Amazon VPC Lattice is an application networking service that simplifies service-to-service communication across VPCs and AWS accounts.
VPC Lattice operates at Layer 4 (TCP) and Layer 7 (HTTP/HTTPS) to provide intelligent application-layer routing.
VPC Lattice eliminates the need for complex networking configurations, Transit Gateways, or sidecar-based service meshes.
Key Capabilities
Service-to-service connectivity across VPCs and accounts without IP address management
Built-in service discovery and routing
Application-layer authentication and authorization
Centralized observability and monitoring
Zero-trust security model with fine-grained access controls
Service Networks
Logical container for grouping related services
Provides consistent security policies across services
Can be shared across AWS accounts using AWS Resource Access Manager (RAM)
Enables cross-account connectivity at scale
VPC can have only one service network association
VPC Lattice vs Traditional Networking
Simpler than Transit Gateway for service-to-service communication
No need for VPC Peering connections between every VPC pair
Application-aware routing based on headers, paths, and methods
Automatic service discovery without DNS management
Built-in security without managing security groups across VPCs
Migration from AWS App Mesh
AWS App Mesh is being discontinued effective September 30, 2026
VPC Lattice is the recommended replacement for App Mesh workloads
VPC Lattice provides similar service mesh capabilities without sidecar proxies
Simplified architecture with centralized management
VPC Lattice integrates with Amazon ECS, EKS, EC2, Lambda, and other compute services.
Resource Configurations (Enhanced 2025-2026)
Defines private endpoints (IP address or DNS name) within a VPC for cross-account access
Supports custom domain names for resource configurations (November 2025)
Supports private domain-name targets for secure cross-account access to privately-hosted resources (May 2026)
Attached to resource gateways and shared via AWS RAM
Use cases include microservices architectures, multi-account applications, and hybrid cloud connectivity.
AWS Network Firewall
AWS Network Firewall is a fully managed network security service that protects VPCs from network threats.
Network Firewall provides enterprise-grade perimeter defense with deep packet inspection and intrusion prevention.
Key Features
Stateful and stateless firewall rules
Deep packet inspection (DPI) for Layer 7 traffic analysis
Intrusion detection and prevention system (IDS/IPS)
Domain name filtering and URL filtering
Protocol detection and blocking
Geographic IP filtering
Flexible Rules Engine
Supports thousands of custom firewall rules
Rules based on domain, port, protocol, IP addresses, and pattern matching
Suricata-compatible IPS rules for threat detection
AWS Managed Threat Signatures for known threats
Active threat defense against command-and-control channels and malicious URLs
Traffic Filtering Capabilities
Inbound and outbound web filtering for HTTP/HTTPS traffic
Server Name Indication (SNI) filtering for encrypted traffic
Application protocol detection and enforcement
Malware and botnet protection
DDoS attack mitigation
Deployment and Scalability
Deployed at VPC subnet boundaries
Automatically scales based on traffic load
High availability with 99.99% SLA
Multi-AZ deployment for redundancy
No capacity planning required
Logging and Monitoring
Detailed flow logs for all inspected traffic
Alert logs for detected threats
Integration with CloudWatch, S3, and Kinesis Data Firehose
Real-time visibility into network traffic patterns
Compliance reporting and audit trails
Network Firewall integrates with AWS Firewall Manager for centralized policy management across multiple accounts and VPCs.
Default Stateful Action Update (June 2026)
New default stateful action for firewall policies changed to “Application drop established (server-directed only)” replacing “Application drop established (bidirectional)”
Improves connection reliability for legitimate traffic
Applies to all newly created firewall policies
Common use cases include perimeter security, egress filtering, threat prevention, and compliance enforcement.
AWS Certification Exam Practice Questions
Questions are collected from Internet and the answers are marked as per my knowledge and understanding (which might differ with yours).
AWS services are updated everyday and both the answers and questions might be outdated soon, so research accordingly.
AWS exam questions are not updated to keep up the pace with AWS updates, so even if the underlying feature has changed the question might not be updated
Open to further feedback, discussion and correction.
You have a business-to-business web application running in a VPC consisting of an Elastic Load Balancer (ELB), web servers, application servers and a database. Your web application should only accept traffic from predefined customer IP addresses. Which two options meet this security requirement? Choose 2 answers
Configure web server VPC security groups to allow traffic from your customers’ IPs (Web server is behind the ELB and customer IPs will never reach web servers)
Configure your web servers to filter traffic based on the ELB’s “X-forwarded-for” header (get the customer IPs and create a custom filter to restrict access. Refer link)
Configure ELB security groups to allow traffic from your customers’ IPs and deny all outbound traffic (ELB will see the customer IPs so can restrict access, deny all is basically have no rules in outbound traffic, implicit, and its stateful so would work)
Configure a VPC NACL to allow web traffic from your customers’ IPs and deny all outbound traffic (NACL is stateless, deny all will not work)
A user has created a VPC with public and private subnets using the VPC Wizard. The VPC has CIDR 20.0.0.0/16. The private subnet uses CIDR 20.0.0.0/24. Which of the below mentioned entries are required in the main route table to allow the instances in VPC to communicate with each other?
Destination : 20.0.0.0/24 and Target : VPC
Destination : 20.0.0.0/16 and Target : ALL
Destination : 20.0.0.0/0 and Target : ALL
Destination : 20.0.0.0/16 and Target : Local
A user has created a VPC with two subnets: one public and one private. The user is planning to run the patch update for the instances in the private subnet. How can the instances in the private subnet connect to the internet?
Use the internet gateway with a private IP
Allow outbound traffic in the security group for port 80 to allow internet updates
The private subnet can never connect to the internet
Use NAT with an elastic IP
A user has launched an EC2 instance and installed a website with the Apache webserver. The webserver is running but the user is not able to access the website from the Internet. What can be the possible reason for this failure?
The security group of the instance is not configured properly.
The instance is not configured with the proper key-pairs.
The Apache website cannot be accessed from the Internet.
Instance is not configured with an elastic IP.
A user has created a VPC with public and private subnets using the VPC wizard. Which of the below mentioned statements is true in this scenario?
AWS VPC will automatically create a NAT instance with the micro size
VPC bounds the main route table with a private subnet and a custom route table with a public subnet
User has to manually create a NAT instance
VPC bounds the main route table with a public subnet and a custom route table with a private subnet
A user has created a VPC with public and private subnets. The VPC has CIDR 20.0.0.0/16. The private subnet uses CIDR 20.0.1.0/24 and the public subnet uses CIDR 20.0.0.0/24. The user is planning to host a web server in the public subnet (port 80) and a DB server in the private subnet (port 3306). The user is configuring a security group of the NAT instance. Which of the below mentioned entries is not required for the NAT security group?
For Inbound allow Source: 20.0.1.0/24 on port 80
For Outbound allow Destination: 0.0.0.0/0 on port 80
For Inbound allow Source: 20.0.0.0/24 on port 80
For Outbound allow Destination: 0.0.0.0/0 on port 443
A user has created a VPC with CIDR 20.0.0.0/24. The user has used all the IPs of CIDR and wants to increase the size of the VPC. The user has two subnets: public (20.0.0.0/25) and private (20.0.0.128/25). How can the user change the size of the VPC?
The user can delete all the instances of the subnet. Change the size of the subnets to 20.0.0.0/32 and 20.0.1.0/32, respectively. Then the user can increase the size of the VPC using CLI
It is not possible to change the size of the VPC once it has been created (NOTE – You can now increase the VPC size. Read Post)
User can add a subnet with a higher range so that it will automatically increase the size of the VPC
User can delete the subnets first and then modify the size of the VPC
A user has created a VPC with the public and private subnets using the VPC wizard. The VPC has CIDR 20.0.0.0/16. The public subnet uses CIDR 20.0.1.0/24. The user is planning to host a web server in the public subnet (port 80) and a DB server in the private subnet (port 3306). The user is configuring a security group for the public subnet (WebSecGrp) and the private subnet (DBSecGrp). Which of the below mentioned entries is required in the web server security group (WebSecGrp)?
Configure Destination as DB Security group ID (DbSecGrp) for port 3306 Outbound
Configure port 80 for Destination 0.0.0.0/0 Outbound
Configure port 3306 for source 20.0.0.0/24 InBound
Configure port 80 InBound for source 20.0.0.0/16
A user has created a VPC with CIDR 20.0.0.0/16. The user has created one subnet with CIDR 20.0.0.0/16 by mistake. The user is trying to create another subnet of CIDR 20.0.0.1/24. How can the user create the second subnet?
There is no need to update the subnet as VPC automatically adjusts the CIDR of the first subnet based on the second subnet’s CIDR
The user can modify the first subnet CIDR from the console
It is not possible to create a second subnet as one subnet with the same CIDR as the VPC has been created
The user can modify the first subnet CIDR with AWS CLI
A user has setup a VPC with CIDR 20.0.0.0/16. The VPC has a private subnet (20.0.1.0/24) and a public subnet (20.0.0.0/24). The user’s data centre has CIDR of 20.0.54.0/24 and 20.1.0.0/24. If the private subnet wants to communicate with the data centre, what will happen?
It will allow traffic communication on both the CIDRs of the data centre
It will not allow traffic with data centre on CIDR 20.1.0.0/24 but allows traffic communication on 20.0.54.0/24
It will not allow traffic communication on any of the data centre CIDRs
It will allow traffic with data centre on CIDR 20.1.0.0/24 but does not allow on 20.0.54.0/24 (as the CIDR block would be overlapping)
A user has created a VPC with public and private subnets using the VPC wizard. The VPC has CIDR 20.0.0.0/16. The private subnet uses CIDR 20.0.0.0/24 . The NAT instance ID is i-a12345. Which of the below mentioned entries are required in the main route table attached with the private subnet to allow instances to connect with the internet?
Destination: 0.0.0.0/0 and Target: i-a12345
Destination: 20.0.0.0/0 and Target: 80
Destination: 20.0.0.0/0 and Target: i-a12345
Destination: 20.0.0.0/24 and Target: i-a12345
A user has created a VPC with CIDR 20.0.0.0/16 using the wizard. The user has created a public subnet CIDR (20.0.0.0/24) and VPN only subnets CIDR (20.0.1.0/24) along with the VPN gateway (vgw-12345) to connect to the user’s data centre. The user’s data centre has CIDR 172.28.0.0/12. The user has also setup a NAT instance (i-123456) to allow traffic to the internet from the VPN subnet. Which of the below mentioned options is not a valid entry for the main route table in this scenario?
Destination: 20.0.1.0/24 and Target: i-12345
Destination: 0.0.0.0/0 and Target: i-12345
Destination: 172.28.0.0/12 and Target: vgw-12345
Destination: 20.0.0.0/16 and Target: local
A user has created a VPC with CIDR 20.0.0.0/16. The user has created one subnet with CIDR 20.0.0.0/16 in this VPC. The user is trying to create another subnet with the same VPC for CIDR 20.0.0.1/24. What will happen in this scenario?
The VPC will modify the first subnet CIDR automatically to allow the second subnet IP range
It is not possible to create a subnet with the same CIDR as VPC
The second subnet will be created
It will throw a CIDR overlaps error
A user has created a VPC with CIDR 20.0.0.0/16 using the wizard. The user has created both Public and VPN-Only subnets along with hardware VPN access to connect to the user’s data centre. The user has not yet launched any instance as well as modified or deleted any setup. He wants to delete this VPC from the console. Will the console allow the user to delete the VPC?
Yes, the console will delete all the setups and also delete the virtual private gateway
No, the console will ask the user to manually detach the virtual private gateway first and then allow deleting the VPC
Yes, the console will delete all the setups and detach the virtual private gateway
No, since the NAT instance is running
A user has created a VPC with the public and private subnets using the VPC wizard. The VPC has CIDR 20.0.0.0/16. The public subnet uses CIDR 20.0.1.0/24. The user is planning to host a web server in the public subnet (port 80) and a DB server in the private subnet (port 3306). The user is configuring a security group for the public subnet (WebSecGrp) and the private subnet (DBSecGrp). Which of the below mentioned entries is required in the private subnet database security group (DBSecGrp)?
Allow Inbound on port 3306 for Source Web Server Security Group (WebSecGrp)
Allow Inbound on port 3306 from source 20.0.0.0/16
Allow Outbound on port 3306 for Destination Web Server Security Group (WebSecGrp.
Allow Outbound on port 80 for Destination NAT Instance IP
A user has created a VPC with a subnet and a security group. The user has launched an instance in that subnet and attached a public IP. The user is still unable to connect to the instance. The internet gateway has also been created. What can be the reason for the error?
The internet gateway is not configured with the route table
The private IP is not present
The outbound traffic on the security group is disabled
The internet gateway is not configured with the security group
A user has created a subnet in VPC and launched an EC2 instance within it. The user has not selected the option to assign the IP address while launching the instance. Which of the below mentioned statements is true with respect to the Instance requiring access to the Internet?
The instance will always have a public DNS attached to the instance by default
The user can directly attach an elastic IP to the instance
The instance will never launch if the public IP is not assigned
The user would need to create an internet gateway and then attach an elastic IP to the instance to connect from internet
A user has created a VPC with public and private subnets using the VPC wizard. Which of the below mentioned statements is not true in this scenario?
VPC will create a routing instance and attach it with a public subnet
VPC will create two subnets
VPC will create one internet gateway and attach it to VPC
VPC will launch one NAT instance with an elastic IP
A user has created a VPC with the public subnet. The user has created a security group for that VPC. Which of the below mentioned statements is true when a security group is created?
It can connect to the AWS services, such as S3 and RDS by default
It will have all the inbound traffic by default
It will have all the outbound traffic by default
It will by default allow traffic to the internet gateway
A user has created a VPC with CIDR 20.0.0.0/16 using VPC Wizard. The user has created a public CIDR (20.0.0.0/24) and a VPN only subnet CIDR (20.0.1.0/24) along with the hardware VPN access to connect to the user’s data centre. Which of the below mentioned components is not present when the VPC is setup with the wizard?
Main route table attached with a VPN only subnet
A NAT instance configured to allow the VPN subnet instances to connect with the internet
Custom route table attached with a public subnet
An internet gateway for a public subnet
A user has created a VPC with public and private subnets using the VPC wizard. The user has not launched any instance manually and is trying to delete the VPC. What will happen in this scenario?
It will not allow to delete the VPC as it has subnets with route tables
It will not allow to delete the VPC since it has a running route instance
It will terminate the VPC along with all the instances launched by the wizard
It will not allow to delete the VPC since it has a running NAT instance
A user has created a public subnet with VPC and launched an EC2 instance within it. The user is trying to delete the subnet. What will happen in this scenario?
It will delete the subnet and make the EC2 instance as a part of the default subnet
It will not allow the user to delete the subnet until the instances are terminated
It will delete the subnet as well as terminate the instances
Subnet can never be deleted independently, but the user has to delete the VPC first
A user has created a VPC with CIDR 20.0.0.0/24. The user has created a public subnet with CIDR 20.0.0.0/25 and a private subnet with CIDR 20.0.0.128/25. The user has launched one instance each in the private and public subnets. Which of the below mentioned options cannot be the correct IP address (private IP) assigned to an instance in the public or private subnet?
20.0.0.255
20.0.0.132
20.0.0.122
20.0.0.55
A user has created a VPC with CIDR 20.0.0.0/16. The user has created public and VPN only subnets along with hardware VPN access to connect to the user’s datacenter. The user wants to make so that all traffic coming to the public subnet follows the organization’s proxy policy. How can the user make this happen?
Setting up a NAT with the proxy protocol and configure that the public subnet receives traffic from NAT
Setting up a proxy policy in the internet gateway connected with the public subnet
It is not possible to setup the proxy policy for a public subnet
Setting the route table and security group of the public subnet which receives traffic from a virtual private gateway
A user has created a VPC with CIDR 20.0.0.0/16 using the wizard. The user has created a public subnet CIDR (20.0.0.0/24) and VPN only subnets CIDR (20.0.1.0/24) along with the VPN gateway (vgw-12345) to connect to the user’s data centre. Which of the below mentioned options is a valid entry for the main route table in this scenario?
Destination: 20.0.0.0/24 and Target: vgw-12345
Destination: 20.0.0.0/16 and Target: ALL
Destination: 20.0.1.0/16 and Target: vgw-12345
Destination: 0.0.0.0/0 and Target: vgw-12345
Which two components provide connectivity with external networks? When attached to an Amazon VPC which two components provide connectivity with external networks? Choose 2 answers
Elastic IPs (EIP) (Does not provide connectivity, public IP address will do as well)
NAT Gateway (NAT) (Not Attached to VPC and still needs IGW)
Internet Gateway (IGW)
Virtual Private Gateway (VGW)
You are attempting to connect to an instance in Amazon VPC without success You have already verified that the VPC has an Internet Gateway (IGW) the instance has an associated Elastic IP (EIP) and correct security group rules are in place. Which VPC component should you evaluate next?
The configuration of a NAT instance
The configuration of the Routing Table
The configuration of the internet Gateway (IGW)
The configuration of SRC/DST checking
If you want to launch Amazon Elastic Compute Cloud (EC2) Instances and assign each Instance a predetermined private IP address you should:
Assign a group or sequential Elastic IP address to the instances
Launch the instances in a Placement Group
Launch the instances in the Amazon virtual Private Cloud (VPC)
Use standard EC2 instances since each instance gets a private Domain Name Service (DNS) already
Launch the Instance from a private Amazon Machine image (AMI)
A user has recently started using EC2. The user launched one EC2 instance in the default subnet in EC2-VPC Which of the below mentioned options is not attached or available with the EC2 instance when it is launched?
Public IP address
Internet gateway
Elastic IP
Private IP address
A user has created a VPC with CIDR 20.0.0.0/24. The user has created a public subnet with CIDR 20.0.0.0/25. The user is trying to create the private subnet with CIDR 20.0.0.128/25. Which of the below mentioned statements is true in this scenario?
It will not allow the user to create the private subnet due to a CIDR overlap
It will allow the user to create a private subnet with CIDR as 20.0.0.128/25
This statement is wrong as AWS does not allow CIDR 20.0.0.0/25
It will not allow the user to create a private subnet due to a wrong CIDR range
A user has created a VPC with CIDR 20.0.0.0/16 with only a private subnet and VPN connection using the VPC wizard. The user wants to connect to the instance in a private subnet over SSH. How should the user define the security rule for SSH?
Allow Inbound traffic on port 22 from the user’s network
The user has to create an instance in EC2 Classic with an elastic IP and configure the security group of a private subnet to allow SSH from that elastic IP
The user can connect to a instance in a private subnet using the NAT instance
Allow Inbound traffic on port 80 and 22 to allow the user to connect to a private subnet over the Internet
A company wants to implement their website in a virtual private cloud (VPC). The web tier will use an Auto Scaling group across multiple Availability Zones (AZs). The database will use Multi-AZ RDS MySQL and should not be publicly accessible. What is the minimum number of subnets that need to be configured in the VPC?
1
2
3
4 (2 public subnets for web instances in multiple AZs and 2 private subnets for RDS Multi-AZ)
Which of the following are characteristics of Amazon VPC subnets? Choose 2 answers
Each subnet maps to a single Availability Zone
A CIDR block mask of /25 is the smallest range supported
Instances in a private subnet can communicate with the Internet only if they have an Elastic IP.
By default, all subnets can route between each other, whether they are private or public
Each subnet spans at least 2 Availability zones to provide a high-availability environment
You need to design a VPC for a web-application consisting of an Elastic Load Balancer (ELB). a fleet of web/application servers, and an RDS database The entire Infrastructure must be distributed over 2 availability zones. Which VPC configuration works while assuring the database is not available from the Internet?
One public subnet for ELB one public subnet for the web-servers, and one private subnet for the database
One public subnet for ELB two private subnets for the web-servers, two private subnets for RDS
Two public subnets for ELB two private subnets for the web-servers and two private subnets for RDS
Two public subnets for ELB two public subnets for the web-servers, and two public subnets for RDS
You have deployed a three-tier web application in a VPC with a CIDR block of 10.0.0.0/28. You initially deploy two web servers, two application servers, two database servers and one NAT instance tor a total of seven EC2 instances. The web, application and database servers are deployed across two availability zones (AZs). You also deploy an ELB in front of the two web servers, and use Route53 for DNS Web traffic gradually increases in the first few days following the deployment, so you attempt to double the number of instances in each tier of the application to handle the new load unfortunately some of these new instances fail to launch. Which of the following could the root caused? (Choose 2 answers) [PROFESSIONAL]
The Internet Gateway (IGW) of your VPC has scaled-up adding more instances to handle the traffic spike, reducing the number of available private IP addresses for new instance launches.
AWS reserves one IP address in each subnet’s CIDR block for Route53 so you do not have enough addresses left to launch all of the new EC2 instances.
AWS reserves the first and the last private IP address in each subnet’s CIDR block so you do not have enough addresses left to launch all of the new EC2 instances.
The ELB has scaled-up. Adding more instances to handle the traffic reducing the number of available private IP addresses for new instance launches
AWS reserves the first four and the last IP address in each subnet’s CIDR block so you do not have enough addresses left to launch all of the new EC2 instances.
A user wants to access RDS from an EC2 instance using IP addresses. Both RDS and EC2 are in the same region, but different AZs. Which of the below mentioned options help configure that the instance is accessed faster?
Configure the Private IP of the Instance in RDS security group (Recommended as the data is transferred within the the Amazon network and not through internet – Refer link)
Security group of EC2 allowed in the RDS security group
Configuring the elastic IP of the instance in RDS security group
Configure the Public IP of the instance in RDS security group
In regards to VPC, select the correct statement:
You can associate multiple subnets with the same Route Table.
You can associate multiple subnets with the same Route Table, but you can’t associate a subnet with only one Route Table.
You can’t associate multiple subnets with the same Route Table.
None of these.
You need to design a VPC for a web-application consisting of an ELB a fleet of web application servers, and an RDS DB. The entire infrastructure must be distributed over 2 AZ. Which VPC configuration works while assuring the DB is not available from the Internet?
One Public Subnet for ELB, one Public Subnet for the web-servers, and one private subnet for the DB
One Public Subnet for ELB, two Private Subnets for the web-servers, and two private subnets for the RDS
Two Public Subnets for ELB, two private Subnet for the web-servers, and two private subnet for the RDS
Two Public Subnets for ELB, two Public Subnet for the web-servers, and two public subnets for the RDS
You have an Amazon VPC with one private subnet and one public subnet with a Network Address Translator (NAT) server. You are creating a group of Amazon Elastic Cloud Compute (EC2) instances that configure themselves at startup via downloading a bootstrapping script from Amazon Simple Storage Service (S3) that deploys an application via GIT. Which setup provides the highest level of security?
Amazon EC2 instances in private subnet, no EIPs, route outgoing traffic via the NAT
Amazon EC2 instances in public subnet, no EIPs, route outgoing traffic via the Internet Gateway (IGW)
Amazon EC2 instances in private subnet, assign EIPs, route outgoing traffic via the Internet Gateway (IGW)
Amazon EC2 instances in public subnet, assign EIPs, route outgoing traffic via the NAT
You have launched an Amazon Elastic Compute Cloud (EC2) instance into a public subnet with a primary private IP address assigned, an internet gateway is attached to the VPC, and the public route table is configured to send all Internet-based traffic to the Internet gateway. The instance security group is set to allow all outbound traffic but cannot access the Internet. Why is the Internet unreachable from this instance?
The instance does not have a public IP address
The Internet gateway security group must allow all outbound traffic.
The instance security group must allow all inbound traffic.
The instance “Source/Destination check” property must be enabled.
You have an environment that consists of a public subnet using Amazon VPC and 3 instances that are running in this subnet. These three instances can successfully communicate with other hosts on the Internet. You launch a fourth instance in the same subnet, using the same AMI and security group configuration you used for the others, but find that this instance cannot be accessed from the internet. What should you do to enable Internet access?
Deploy a NAT instance into the public subnet.
Assign an Elastic IP address to the fourth instance
Configure a publically routable IP Address in the host OS of the fourth instance.
Modify the routing table for the public subnet.
You have a load balancer configured for VPC, and all back-end Amazon EC2 instances are in service. However, your web browser times out when connecting to the load balancer’s DNS name. Which options are probable causes of this behavior? Choose 2 answers
The load balancer was not configured to use a public subnet with an Internet gateway configured
The Amazon EC2 instances do not have a dynamically allocated private IP address
The security groups or network ACLs are not property configured for web traffic.
The load balancer is not configured in a private subnet with a NAT instance.
The VPC does not have a VGW configured.
When will you incur costs with an Elastic IP address (EIP)?
When an EIP is allocated.
When it is allocated and associated with a running instance.
When it is allocated and associated with a stopped instance.
Costs are incurred regardless of whether the EIP is associated with a running instance.
A company currently has a VPC with EC2 Instances. A new instance being launched, which will host an application that works on IPv6. You need to ensure that this instance can initiate outgoing traffic to the Internet. At the same time, you need to ensure that no incoming connection can be initiated from the Internet on to the instance. Which of the following would you add to the VPC for this requirement?
A NAT Instance
A NAT Gateway
An Internet Gateway
An egress-only Internet gateway
A company is deploying a multi-account AWS environment and needs centralized IP address management across all accounts and regions. Which AWS service should they use?
AWS Config
AWS Systems Manager
Amazon VPC IP Address Manager (IPAM)
AWS Resource Access Manager
An organization wants to enable service-to-service communication across multiple VPCs and AWS accounts without managing complex networking configurations or Transit Gateways. Which service provides this capability?
AWS PrivateLink
VPC Peering
Amazon VPC Lattice
AWS Direct Connect
A security team needs to implement deep packet inspection and intrusion prevention for all traffic entering and leaving their VPC. Which AWS service should they deploy?
AWS WAF
AWS Shield
AWS Network Firewall
Security Groups
Your company is currently using AWS App Mesh for service mesh capabilities. What is the recommended migration path given AWS’s service roadmap?
Migrate to AWS Cloud Map
Migrate to Amazon VPC Lattice (App Mesh EOL September 30, 2026)
Continue using App Mesh indefinitely
Migrate to Elastic Load Balancing
Which of the following features are provided by Amazon VPC Lattice? Choose 3 answers
Built-in service discovery
VPN connectivity
Cross-account service connectivity
Direct Connect integration
Application-layer authentication
A network administrator needs to prevent IP address conflicts across 50 AWS accounts in their organization. They want automated CIDR allocation for new VPCs. Which service feature addresses this requirement?
VPC Flow Logs
AWS VPC IPAM with automated allocation
AWS Config Rules
VPC CIDR block associations
AWS Network Firewall supports which of the following capabilities? Choose 3 answers
Deep packet inspection (DPI)
DDoS protection at Layer 3/4 (use AWS Shield)
Intrusion detection and prevention (IDS/IPS)
Web application firewall rules (use AWS WAF)
Domain name and URL filtering
Your organization needs to integrate AWS IP address management with existing Infoblox infrastructure. Which IPAM tier is required?
IPAM Basic Tier
IPAM Advanced Tier
IPAM Standard Tier
IPAM Enterprise Tier
A company wants to route HTTP traffic between microservices based on request headers and paths across multiple VPCs. Which service provides this capability?
Application Load Balancer
AWS Transit Gateway
Amazon VPC Lattice (Layer 7 routing)
VPC Peering
Which AWS service provides a 99.99% SLA for managed network security with automatic scaling?
Security Groups
Network ACLs
AWS Network Firewall
AWS WAF
A company needs to implement dynamic routing between their network virtual appliances and VPC route tables using BGP, with automatic failover when an appliance becomes unavailable. Which service should they use?
AWS Transit Gateway
Amazon VPC Route Server
AWS Direct Connect
VPC Peering
An organization wants to ensure no resources in specific VPCs can access or be accessed from the Internet, regardless of security group or route table configurations. Which feature provides this declarative control?
Network ACLs with deny rules
Security Group restrictions
VPC Block Public Access (BPA)
AWS WAF IP restrictions
A security team needs to centrally monitor and enforce that all network traffic within their VPCs is encrypted in transit, with audit logs for compliance. Which feature should they enable?
AWS CloudTrail
VPC Flow Logs
VPC Encryption Controls
AWS Config Rules
Which of the following statements about VPC Encryption Controls are correct? Choose 2 answers
It uses Nitro System hardware encryption and application-layer encryption (TLS/SSL)
It encrypts data at rest in EBS volumes
It provides monitor mode to audit encryption status and enforce mode to prevent unencrypted traffic
It requires VPN connections for all traffic
A company needs to tag individual IP address allocations within their IPAM pools to control access via IAM policies. Which IPAM feature supports this?
In a VPC, both Security Groups and Network ACLs (NACLS) together help to build a layered network defence.
Security groups – Act as a virtual firewall for associated instances, controlling both inbound and outbound traffic at the instance level
Network access control lists (NACLs) – Act as a firewall for associated subnets, controlling both inbound and outbound traffic at the subnet level
Security Groups
Acts at an Instance level and not at the subnet level.
Each instance within a subnet can be assigned a different set of Security groups
An instance can be assigned up to 5 security groups (default, can be increased up to 16) with each security group having up to 60 rules (inbound and outbound separately).
allows separate rules for inbound and outbound traffic.
allows adding or removing rules (authorizing or revoking access) for both Inbound (ingress) and Outbound (egress) traffic to the instance
Default Security group allows no external inbound traffic but allows inbound traffic from instances with the same security group
Default Security group allows all outbound traffic
New Security groups start with only an outbound rule that allows all traffic to leave the instances.
can specify only Allow rules, but not deny rules
can grant access to a specific IP, CIDR range, or to another security group in the VPC or in a peer VPC (requires a VPC peering connection)
are evaluated as a Whole or Cumulative bunch of rules with the most permissive rule taking precedence for e.g. if you have a rule that allows access to TCP port 22 (SSH) from IP address 203.0.113.1 and another rule that allows access to TCP port 22 from everyone, everyone has access to TCP port 22.
are Stateful – responses to allowed inbound traffic are allowed to flow outbound regardless of outbound rules, and vice versa. Hence an Outbound rule for the response is not needed
Instances associated with a security group can’t talk to each other unless rules allowing the traffic are added.
are associated with ENI (network interfaces).
are associated with the instance and can be changed, which changes the security groups associated with the primary network interface (eth0) and the changes would be applicable immediately to all the instances associated with the Security Group.
Security Group Quotas
VPC security groups per Region: 2,500 (adjustable)
Inbound or outbound rules per security group: 60 (adjustable, enforced separately for IPv4 and IPv6)
Security groups per network interface: 5 (default, adjustable up to 16)
Total rules per network interface: Maximum of 1,000 rules across all attached security groups (hard limit)
The quota for rules per security group multiplied by security groups per network interface cannot exceed 1,000
Security Group VPC Associations and Sharing (New – 2024)
Security Group VPC Associations allow associating a security group with multiple VPCs in the same account and Region, enabling consistent security rules across workloads in different VPCs without duplicating security groups.
Shared Security Groups allow the VPC owner to share security groups with participant accounts in a shared VPC using AWS Resource Access Manager (RAM).
Participant accounts can use the shared security groups but cannot modify them.
Shared security groups can only be used with resources in shared subnets of the owner’s VPC.
Cannot be used with default security groups or default VPCs.
These features complement security group referencing across VPC peering and Transit Gateway.
VPC Peering: Can reference security groups in a peer VPC within the same Region.
Transit Gateway (Sep 2024): Can reference security groups from other VPCs attached to the same Transit Gateway within the same Region, eliminating the need to hard-code IP address ranges.
Cloud WAN (Jun 2025): Can reference security groups defined in other VPCs within the same Region attached to the same Cloud WAN core network.
Security group referencing allows rules to dynamically adapt as instances scale up/down without updating IP-based rules.
Connection Tracking
Security groups are Stateful as they use Connection tracking to track information about traffic to and from the instance.
Responses to inbound traffic are allowed to flow out of the instance regardless of outbound security group rules, and vice versa.
Connection Tracking is maintained only if there is no explicit Outbound rule for an Inbound request (and vice versa)
However, if there is an explicit Outbound rule for an Inbound request, the response traffic is allowed on the basis of the Outbound rule and not on the Tracking information
Tracking flow e.g.
If an instance (host A) initiates traffic to host B and uses a protocol other than TCP, UDP, or ICMP, the instance’s firewall only tracks the IP address & protocol number for the purpose of allowing response traffic from host B.
If host B initiates traffic to the instance in a separate request within 600 seconds of the original request or response, the instance accepts it regardless of inbound security group rules, because it’s regarded as response traffic.
This can be controlled by modifying the security group’s outbound rules to permit only certain types of outbound traffic. Alternatively, Network ACLs (NACLs) can be used for the subnet, network ACLs are stateless and therefore do not automatically allow response traffic.
Connection Tracking Idle Timeouts (Configurable)
Connection tracking idle timeouts are configurable per Elastic Network Interface (ENI) since Nov 2023.
TCP Established timeout:
Default: 432,000 seconds (5 days) for most instance types
Default: 350 seconds for Nitro V6 instance types (since Jun 2025)
Recommended: Less than 432,000 seconds to prevent connection tracking table exhaustion
UDP Stream timeout (bidirectional traffic): Min 60s, Max 180s, Default 180s
UDP Unidirectional timeout: Min 30s, Max 60s, Default 30s
Configurable timeouts help prevent connection tracking exhaustion for high-throughput workloads, DNS-heavy UDP workloads, and long-lived idle connections.
Network Access Control Lists – NACLs
A Network ACLs (NACLs) is an optional layer of security for the VPC that acts as a firewall for controlling traffic in and out of one or more subnets.
are not for granular control and are assigned at a Subnet level and are applicable to all the instances in that Subnet
has separate inbound and outbound rules, and each rule can either allow or deny traffic
Default ACL allows all inbound and outbound traffic.
The newly created ACL denies all inbound and outbound traffic.
A Subnet can be assigned only 1 NACL and if not associated explicitly would be associated implicitly with the default NACL
can associate a network ACL with multiple subnets
is a numbered list of rules that are evaluated in order starting with the lowest numbered rule, to determine whether traffic is allowed in or out of any subnet associated with the network ACL e.g. if you have a Rule No. 100 with Allow All and 110 with Deny All, the Allow All would take precedence and all the traffic will be allowed.
are Stateless; responses to allowed inbound traffic are subject to the rules for outbound traffic (and vice versa) for e.g. if you enable Inbound SSH on port 22 from the specific IP address, you would need to add an Outbound rule for the response as well.
Network ACL Quotas
Network ACLs per VPC: 200 (adjustable)
Rules per network ACL: 20 (adjustable up to 40 inbound and 40 outbound, total 80 rules)
Note: Increasing rules beyond 40 per direction may impact network performance
Security Group vs NACLs
AWS Certification Exam Practice Questions
Questions are collected from Internet and the answers are marked as per my knowledge and understanding (which might differ with yours).
AWS services are updated everyday and both the answers and questions might be outdated soon, so research accordingly.
AWS exam questions are not updated to keep up the pace with AWS updates, so even if the underlying feature has changed the question might not be updated
Open to further feedback, discussion and correction.
Instance A and instance B are running in two different subnets A and B of a VPC. Instance A is not able to ping instance B. What are two possible reasons for this? (Pick 2 correct answers)
The routing table of subnet A has no target route to subnet B
The security group attached to instance B does not allow inbound ICMP traffic
The policy linked to the IAM role on instance A is not configured correctly
The NACL on subnet B does not allow outbound ICMP traffic
An instance is launched into a VPC subnet with the network ACL configured to allow all inbound traffic and deny all outbound traffic. The instance’s security group is configured to allow SSH from any IP address and deny all outbound traffic. What changes need to be made to allow SSH access to the instance?
The outbound security group needs to be modified to allow outbound traffic.
The outbound network ACL needs to be modified to allow outbound traffic.
Nothing, it can be accessed from any IP address using SSH.
Both the outbound security group and outbound network ACL need to be modified to allow outbound traffic.
From what services I can block incoming/outgoing IPs?
Security Groups
DNS
ELB
VPC subnet
IGW
NACL
What is the difference between a security group in VPC and a network ACL in VPC (chose 3 correct answers)
Security group restricts access to a Subnet while ACL restricts traffic to EC2
Security group restricts access to EC2 while ACL restricts traffic to a subnet
Security group can work outside the VPC also while ACL only works within a VPC
Network ACL performs stateless filtering and Security group provides stateful filtering
Security group can only set Allow rule, while ACL can set Deny rule also
You are currently hosting multiple applications in a VPC and have logged numerous port scans coming in from a specific IP address block. Your security team has requested that all access from the offending IP address block be denied for the next 24 hours. Which of the following is the best method to quickly and temporarily deny access from the specified IP address block?
Create an AD policy to modify Windows Firewall settings on all hosts in the VPC to deny access from the IP address block
Modify the Network ACLs associated with all public subnets in the VPC to deny access from the IP address block
Add a rule to all of the VPC 5 Security Groups to deny access from the IP address block
Modify the Windows Firewall settings on all Amazon Machine Images (AMIs) that your organization uses in that VPC to deny access from the IP address block
You have two Elastic Compute Cloud (EC2) instances inside a Virtual Private Cloud (VPC) in the same Availability Zone (AZ) but in different subnets. One instance is running a database and the other instance an application that will interface with the database. You want to confirm that they can talk to each other for your application to work properly. Which two things do we need to confirm in the VPC settings so that these EC2 instances can communicate inside the VPC? Choose 2 answers
A network ACL that allows communication between the two subnets.
Both instances are the same instance class and using the same Key-pair.
That the default route is set to a NAT instance or Internet Gateway (IGW) for them to communicate.
Security groups are set to allow the application host to talk to the database on the right port/protocol
A benefits enrollment company is hosting a 3-tier web application running in a VPC on AWS, which includes a NAT (Network Address Translation) instance in the public Web tier. There is enough provisioned capacity for the expected workload tor the new fiscal year benefit enrollment period plus some extra overhead Enrollment proceeds nicely for two days and then the web tier becomes unresponsive, upon investigation using CloudWatch and other monitoring tools it is discovered that there is an extremely large and unanticipated amount of inbound traffic coming from a set of 15 specific IP addresses over port 80 from a country where the benefits company has no customers. The web tier instances are so overloaded that benefit enrollment administrators cannot even SSH into them. Which activity would be useful in defending against this attack?
Create a custom route table associated with the web tier and block the attacking IP addresses from the IGW (internet Gateway)
Change the EIP (Elastic IP Address) of the NAT instance in the web tier subnet and update the Main Route Table with the new EIP
Create 15 Security Group rules to block the attacking IP addresses over port 80
Create an inbound NACL (Network Access control list) associated with the web tier subnet with deny rules to block the attacking IP addresses
Which of the following statements describes network ACLs? (Choose 2 answers)
Responses to allowed inbound traffic are allowed to flow outbound regardless of outbound rules, and vice versa (are stateless)
Using network ACLs, you can deny access from a specific IP range
Keep network ACL rules simple and use a security group to restrict application level access
NACLs are associated with a single Availability Zone (associated with Subnet)
You are designing security inside your VPC. You are considering the options for establishing separate security zones and enforcing network traffic rules across different zone to limit Instances can communications. How would you accomplish these requirements? Choose 2 answers
Configure a security group for every zone. Configure a default allow all rule. Configure explicit deny rules for the zones that shouldn’t be able to communicate with one another (Security group does not allow deny rules)
Configure you instances to use pre-set IP addresses with an IP address range every security zone. Configure NACL to explicitly allow or deny communication between the different IP address ranges, as required for interzone communication
Configure a security group for every zone. Configure allow rules only between zone that need to be able to communicate with one another. Use implicit deny all rule to block any other traffic
Configure multiple subnets in your VPC, one for each zone. Configure routing within your VPC in such a way that each subnet only has routes to other subnets with which it needs to communicate, and doesn’t have routes to subnets with which it shouldn’t be able to communicate. (default routes are unmodifiable)
Your entire AWS infrastructure lives inside of one Amazon VPC. You have an Infrastructure monitoring application running on an Amazon instance in Availability Zone (AZ) A of the region, and another application instance running in AZ B. The monitoring application needs to make use of ICMP ping to confirm network reachability of the instance hosting the application. Can you configure the security groups for these instances to only allow the ICMP ping to pass from the monitoring instance to the application instance and nothing else” If so how?
No Two instances in two different AZ’s can’t talk directly to each other via ICMP ping as that protocol is not allowed across subnet (i.e. broadcast) boundaries (Can communicate)
Yes Both the monitoring instance and the application instance have to be a part of the same security group, and that security group needs to allow inbound ICMP (Need not have to be part of same security group)
Yes, The security group for the monitoring instance needs to allow outbound ICMP and the application instance’s security group needs to allow Inbound ICMP (is stateful, so just allow outbound ICMP from monitoring and inbound ICMP on monitored instance)
Yes, Both the monitoring instance’s security group and the application instance’s security group need to allow both inbound and outbound ICMP ping packets since ICMP is not a connection-oriented protocol (Security groups are stateful)
A user has configured a VPC with a new subnet. The user has created a security group. The user wants to configure that instances of the same subnet communicate with each other. How can the user configure this with the security group?
There is no need for a security group modification as all the instances can communicate with each other inside the same subnet
Configure the subnet as the source in the security group and allow traffic on all the protocols and ports
Configure the security group itself as the source and allow traffic on all the protocols and ports
The user has to use VPC peering to configure this
You are designing a data leak prevention solution for your VPC environment. You want your VPC Instances to be able to access software depots and distributions on the Internet for product updates. The depots and distributions are accessible via third party CDNs by their URLs. You want to explicitly deny any other outbound connections from your VPC instances to hosts on the Internet. Which of the following options would you consider?
Configure a web proxy server in your VPC and enforce URL-based rules for outbound access Remove default routes. (Security group and NACL cannot have URLs in the rules nor does the route)
Implement security groups and configure outbound rules to only permit traffic to software depots.
Move all your instances into private VPC subnets remove default routes from all routing tables and add specific routes to the software depots and distributions only.
Implement network access control lists to all specific destinations, with an Implicit deny as a rule.
You have an EC2 Security Group with several running EC2 instances. You change the Security Group rules to allow inbound traffic on a new port and protocol, and launch several new instances in the same Security Group. The new rules apply:
Immediately to all instances in the security group.
Immediately to the new instances only.
Immediately to the new instances, but old instances must be stopped and restarted before the new rules apply.
To all instances, but it may take several minutes for old instances to see the changes.
A company has multiple VPCs in the same AWS account and Region. They want to apply the same security group rules consistently across all VPCs without duplicating security groups. Which feature should they use?
VPC Peering with security group referencing
Security Group VPC Associations
AWS Transit Gateway security group referencing
AWS Firewall Manager common security group policy
An organization uses VPC sharing with multiple participant accounts. The VPC owner wants to enforce consistent security group rules on all participant workloads while preventing participants from modifying the rules. Which approach meets this requirement?
Create security groups in each participant account and use AWS Config rules for compliance
Use AWS Firewall Manager to create audit security group policies
Share security groups from the VPC owner account to participant accounts using AWS RAM
Create identical security groups in each participant account using CloudFormation StackSets
An application running on Nitro V6 instances is experiencing dropped connections after being idle for about 6 minutes. The security groups allow all required traffic. What is the most likely cause?
The NACL outbound rules are blocking the return traffic
The security group inbound rules need to be updated
The TCP established idle timeout on Nitro V6 instances defaults to 350 seconds, and the connection is being dropped by connection tracking