AWS Cloud Migration Services

AWS Cloud Migration Services

  • AWS Cloud Migration services help to address a lot of common use cases such as
    • cloud migration,
    • disaster recovery,
    • data center decommission, and
    • content distribution.
  • For migrating data from on-premises to AWS, the major aspect for consideration are
    • amount of data and network speed
    • data security in transit
    • existing application knowledge for recreation

Application & Database Cloud Migration Services

AWS Migration Hub

  • provides a centralized, single place to discover the existing servers, plan migrations, and track the status of each application migration.
  • provides visibility into the application portfolio and streamlines planning and tracking.
  • helps visualize the connections and the status of the migrating servers and databases, regardless of which migration tool is used.
  • stores all the data in the selected Home Region and provides a single repository of discovery and migration planning information for the entire portfolio and a single view of migrations into multiple AWS Regions.
  • helps track the status of the migrations in all AWS Regions, provided the migration tools are available in that Region.
  • helps understand the environment by letting you explore information collected by AWS discovery tools and stored in the AWS Application Discovery Service’s repository.
  • supports migration status updates from the following tools:
  • migration tools send migration status to the selected Home Region
  • supports EC2 instance recommendations, that provide you with the ability to estimate the cost of running the existing servers in AWS.
  • supports Strategy Recommendations, that help easily build a migration and modernization strategy for the applications running on-premises or in AWS.

AWS Application Discovery Service

  • AWS Application Discovery Service helps plan migration to the AWS cloud by collecting usage and configuration data about the on-premises servers.
  • helps enterprises obtain a snapshot of the current state of their data center servers by collecting server specification information, hardware configuration, performance data, details of running processes, and network connections
  • is integrated with AWS Migration Hub,
    • which simplifies migration tracking as it aggregates migration status information into a single console.
    • can help view the discovered servers, group them into applications, and then track the migration status of each application.
  • discovered data for all the regions is stored in the AWS Migration Hub home Region.
  • The data can be exported for analysis in Microsoft Excel or AWS analysis tools such as Amazon Athena and Amazon QuickSight.
  • supports both agent and agentless-based on-premises tooling, in addition to file-based import for performing discovery and collecting data about the on-premises servers.

AWS Server Migration Service (SMS)

  • is an agentless service that makes it easier and faster to migrate thousands of on-premises workloads to AWS.
  • helps automate, schedule, and track incremental replications of live server volumes, making it easier to coordinate large-scale server migrations.
  • currently supports migration of virtual machines from VMware vSphere,  Windows Hyper-V and Azure VM to AWS
  • supports migrating Windows Server 2003, 2008, 2012, and 2016, and Windows 7, 8, and 10; Red Hat Enterprise Linux (RHEL), SUSE/SLES, CentOS, Ubuntu, Oracle Linux, Fedora, and Debian Linux OS
  • replicates each server volume, which is saved as a new AMI, which can be launched as an EC2 instance
  • is a significant enhancement of EC2 VM Import/Export service
  • is used to Re-host

AWS Database Migration Service (DMS)

  • helps migrate databases to AWS quickly and securely.
  • source database remains fully operational during the migration, minimizing downtime to applications that rely on the database.
  • supports homogeneous migrations such as Oracle to Oracle, as well as heterogeneous migrations between different database platforms, such as Oracle or Microsoft SQL Server to Amazon Aurora.
  • monitors for replication tasks, network or host failures, and automatically provisions a host replacement in case of failures that can’t be repaired
  • supports both one-time data migration into RDS and EC2-based databases as well as for continuous data replication
  • supports continuous replication of the data with high availability and consolidate databases into a petabyte-scale data warehouse by streaming data to Amazon Redshift and Amazon S3
  • provides free AWS Schema Conversion Tool (SCT) that automates the conversion of Oracle PL/SQL and SQL Server T-SQL code to equivalent code in the Amazon Aurora / MySQL dialect of SQL or the equivalent PL/pgSQL code in PostgreSQL

AWS EC2 VM Import/Export

  • allows easy import of virtual machine images from existing environment to EC2 instances and export them back to on-premises environment
  • allows leveraging of existing investments in the virtual machines, built to meet compliance requirements, configuration management and IT security by bringing those virtual machines into EC2 as ready-to-use instances
  • Common usages include
    • Migrate Existing Applications and Workloads to EC2, allowing preserving of the software and settings configured in the existing VMs.
    • Copy Your VM Image Catalog to EC2
    • Create a Disaster Recovery Repository for your VM images

Data Transfer Services

VPN

  • connection utilizes IPSec to establish encrypted network connectivity between on-premises network and VPC over the Internet.
  • connections can be configured in minutes and a good solution for an immediate need, have low to modest bandwidth requirements, and can tolerate the inherent variability in Internet-based connectivity.
  • still requires internet and be configured using VGW and CGW

AWS Direct Connect

  • provides a dedicated physical connection between the corporate network and AWS Direct Connect location with no data transfer over the Internet.
  • helps bypass Internet service providers (ISPs) in the network path
  • helps reduce network costs, increase bandwidth throughput, and provide a more consistent network experience than with Internet-based connection
  • takes time to setup and involves third parties
  • are not redundant and would need another direct connect connection or a VPN connection
  •  Security
    • provides a dedicated physical connection without internet
    • For additional security can be used with VPN

AWS Import/Export (upgraded to Snowball)

  • accelerates moving large amounts of data into and out of AWS using secure Snowball appliances
  • AWS transfers the data directly onto and off of the storage devices using Amazon’s high-speed internal network, bypassing the Internet
  • Data Migration
    • for significant data size, AWS Import/Export is faster than Internet transfer is and more cost-effective than upgrading the connectivity
    • if loading the data over the Internet would take a week or more, AWS Import/Export should be considered
    • data from appliances can be imported to S3, Glacier and EBS volumes and exported from S3
    • not suitable for applications that cannot tolerate offline transfer time
  •  Security
    • Snowball uses an industry-standard Trusted Platform Module (TPM) that has a dedicated processor designed to detect any unauthorized modifications to the hardware, firmware, or software to physically secure the AWS Snowball device.

Snow Family

  • AWS Snowball
    • is a petabyte-scale data transfer service built around a secure suitcase-sized device that moves data into and out of the AWS Cloud quickly and efficiently.
    • transfers the data to S3 bucket
    • transfer times are about a week from start to finish.
    • are commonly used to ship terabytes or petabytes of analytics data, healthcare and life sciences data, video libraries, image repositories, backups, and archives as part of data center shutdown, tape replacement, or application migration projects.
  • AWS Snowball Edge devices
    • contain slightly larger capacity and an embedded computing platform that helps perform simple processing tasks.
    • can be rack shelved and may also be clustered together, making it simpler to collect and store data in extremely remote locations.
    • commonly used in environments with intermittent connectivity (such as manufacturing, industrial, and transportation); or in extremely remote locations (such as military or maritime operations) before shipping them back to AWS data centers.
    • delivers serverless computing applications at the network edge using AWS Greengrass and Lambda functions.
    • common use cases include capturing IoT sensor streams, on-the-fly media transcoding, image compression, metrics aggregation and industrial control signaling and alarming.
  • AWS Snowmobile
    • moves up to 100PB of data (equivalent to 1,250 AWS Snowball devices) in a 45-foot long ruggedized shipping container and is ideal for multi-petabyte or Exabyte-scale digital media migrations and datacenter shutdowns.
    • arrives at the customer site and appears as a network-attached data store for more secure, high-speed data transfer. After data is transferred to Snowmobile, it is driven back to an AWS Region where the data is loaded into S3.
    • is tamper-resistant, waterproof, and temperature controlled with multiple layers of logical and physical security — including encryption, fire suppression, dedicated security personnel, GPS tracking, alarm monitoring, 24/7 video surveillance, and an escort security vehicle during transit.

AWS Storage Gateway

  • connects an on-premises software appliance with cloud-based storage to provide seamless and secure integration between an organization’s on-premises IT environment and the AWS storage infrastructure
  • provides low-latency performance by maintaining frequently accessed data on-premises while securely storing all of the data encrypted in S3 or Glacier.
  • for disaster recovery scenarios, Storage Gateway, together with EC2, can serve as a cloud-hosted solution that mirrors the entire production environment
  • Data Migration
    • with gateway-cached volumes, S3 can be used to hold primary data while frequently accessed data is cached locally for faster access reducing the need to scale on premises storage infrastructure
    • with gateway-stored volumes, entire data is stored locally while asynchronously backing up data to S3
    • with gateway-VTL, offline data archiving can be performed by presenting existing backup application with an iSCSI-based VTL consisting of a virtual media changer and virtual tape drives
  •  Security
    • Encrypts all data in transit to and from AWS by using SSL/TLS.
    • All data in AWS Storage Gateway is encrypted at rest using AES-256.
    • Authentication between the gateway and iSCSI initiators can be secured by using Challenge-Handshake Authentication Protocol (CHAP).

Simple Storage Service – S3

  • Data Transfer
    • Files up to 5GB can be transferred using single operation
    • Multipart uploads can be used to upload files up to 5 TB and speed up data uploads by dividing the file into multiple parts
    • transfer rate still limited by the network speed
  •  Security
    • Data in transit can be secured by using SSL/TLS or client-side encryption.
    • Encrypt data at-rest by performing server-side encryption using Amazon S3-Managed Keys (SSE-S3), AWS Key Management Service (KMS)-Managed Keys (SSE-KMS), or Customer Provided Keys (SSE-C). Or by performing client-side encryption using AWS KMS–Managed Customer Master Key (CMK) or Client-Side Master Key.

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.
  • 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.
  1. Your must architect the migration of a web application to AWS. The application consists of Linux web servers running a custom web server. You are required to save the logs generated from the application to a durable location. What options could you select to migrate the application to AWS? (Choose 2)
    1. Create an AWS Elastic Beanstalk application using the custom web server platform. Specify the web server executable and the application project and source files. Enable log file rotation to Amazon Simple Storage Service (S3). (EB does not work with Custom server executable)
    2. Create Dockerfile for the application. Create an AWS OpsWorks stack consisting of a custom layer. Create custom recipes to install Docker and to deploy your Docker container using the Dockerfile. Create custom recipes to install and configure the application to publish the logs to Amazon CloudWatch Logs (although this is one of the option, the last sentence mentions configure the application to push the logs to S3, which would need changes to application as it needs to use SDK or CLI)
    3. Create Dockerfile for the application. Create an AWS OpsWorks stack consisting of a Docker layer that uses the Dockerfile. Create custom recipes to install and configure Amazon Kinesis to publish the logs into Amazon CloudWatch. (Kinesis not needed)
    4. Create a Dockerfile for the application. Create an AWS Elastic Beanstalk application using the Docker platform and the Dockerfile. Enable logging the Docker configuration to automatically publish the application logs. Enable log file rotation to Amazon S3. (Use Docker configuration with awslogs and EB with Docker)
    5. Use VM import/Export to import a virtual machine image of the server into AWS as an AMI. Create an Amazon Elastic Compute Cloud (EC2) instance from AMI, and install and configure the Amazon CloudWatch Logs agent. Create a new AMI from the instance. Create an AWS Elastic Beanstalk application using the AMI platform and the new AMI. (Use VM Import/Export to create AMI and CloudWatch logs agent to log)
  2. Your company hosts an on-premises legacy engineering application with 900GB of data shared via a central file server. The engineering data consists of thousands of individual files ranging in size from megabytes to multiple gigabytes. Engineers typically modify 5-10 percent of the files a day. Your CTO would like to migrate this application to AWS, but only if the application can be migrated over the weekend to minimize user downtime. You calculate that it will take a minimum of 48 hours to transfer 900GB of data using your company’s existing 45-Mbps Internet connection. After replicating the application’s environment in AWS, which option will allow you to move the application’s data to AWS without losing any data and within the given timeframe?
    1. Copy the data to Amazon S3 using multiple threads and multi-part upload for large files over the weekend, and work in parallel with your developers to reconfigure the replicated application environment to leverage Amazon S3 to serve the engineering files. (Still limited by 45 Mbps speed with minimum 48 hours when utilized to max)
    2. Sync the application data to Amazon S3 starting a week before the migration, on Friday morning perform a final sync, and copy the entire data set to your AWS file server after the sync completes. (Works best as the data changes can be propagated over the week and are fractional and downtime would be know)
    3. Copy the application data to a 1-TB USB drive on Friday and immediately send overnight, with Saturday delivery, the USB drive to AWS Import/Export to be imported as an EBS volume, mount the resulting EBS volume to your AWS file server on Sunday. (Downtime is not known when the data upload would be done, although Amazon says the same day the package is received)
    4. Leverage the AWS Storage Gateway to create a Gateway-Stored volume. On Friday copy the application data to the Storage Gateway volume. After the data has been copied, perform a snapshot of the volume and restore the volume as an EBS volume to be attached to your AWS file server on Sunday. (Still uses the internet)
  3. You are tasked with moving a legacy application from a virtual machine running inside your datacenter to an Amazon VPC. Unfortunately this app requires access to a number of on-premises services and no one who configured the app still works for your company. Even worse there’s no documentation for it. What will allow the application running inside the VPC to reach back and access its internal dependencies without being reconfigured? (Choose 3 answers)
    1. An AWS Direct Connect link between the VPC and the network housing the internal services
    2. An Internet Gateway to allow a VPN connection. (Virtual and Customer gateway is needed)
    3. An Elastic IP address on the VPC instance
    4. An IP address space that does not conflict with the one on-premises
    5. Entries in Amazon Route 53 that allow the Instance to resolve its dependencies’ IP addresses
    6. A VM Import of the current virtual machine
  4. An enterprise runs 103 line-of-business applications on virtual machines in an on-premises data center. Many of the applications are simple PHP, Java, or Ruby web applications, are no longer actively developed, and serve little traffic. Which approach should be used to migrate these applications to AWS with the LOWEST infrastructure costs?
    1. Deploy the applications to single-instance AWS Elastic Beanstalk environments without a load balancer.
    2. Use AWS SMS to create AMIs for each virtual machine and run them in Amazon EC2.
    3. Convert each application to a Docker image and deploy to a small Amazon ECS cluster behind an Application Load Balancer.
    4. Use VM Import/Export to create AMIs for each virtual machine and run them in single-instance AWS Elastic Beanstalk environments by configuring a custom image.

References

AWS VPN

AWS VPC VPN

  • 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) 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
    • 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

VPN Components

AWS VPN Components

  • Virtual Private Gateway – VGW
    • A virtual private gateway is the VPN concentrator on the AWS side of the VPN connection
  • 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.
  • 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 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.
  • 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
    • does not support S3, DynamoDB access through VPC Gateway Endpoint
    • However, Internet connectivity through NAT instance and VPC Interface Endpoint or PrivateLink services are accessible.
  • provides a bandwidth of 1.25 Gbps, currently.

VPN Monitoring

  • AWS Site-to-Site VPN automatically sends notifications to the AWS 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.
    • TunnelDataOut
      • The bytes sent from the AWS side of the connection through the VPN tunnel to the customer gateway.

VPN Connection Redundancy

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 allow gateways on both sides to determine which tunnels are available and reroute traffic if a failure occurs.

Multiple Site-to-Site VPN Connections

VPN Connection

  • 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

VPN CloudHub Architecture

  • 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.

VPN vs Direct Connect

AWS Direct Connect vs VPN

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.
  1. 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?
    1. you can have redundant customer gateways between your data center and your VPC
    2. you can have multiple locations connected to the AWS VPN CloudHub
    3. You have to define 5 different static IP addresses in route table.
    4. 1 and 2
    5. 1,2 and 3
  2. 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?
    1. You can not create more than 1 VPN connections with single VPC (Can be created)
    2. You can not create more than 10 VPN connections with single VPC (soft limit can be extended)
    3. 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)
    4. Statically assigned routes cannot be configured in case of more than 1 VPN with the virtual private gateway. (can be configured)
    5. None of above
  3. 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?
    1. Add another VGW in a different Availability Zone and create another dual-tunnel VPN connection.
    2. Add another CGW in a different data center and create another dual-tunnel VPN connection. (Refer link)
    3. Add a second VGW in a different Availability Zone, and a CGW in a different data center, and create another dual-tunnel.
    4. No changes are necessary: the network architecture is currently highly available.
  4. 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]
    1. 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)
    2. Implement Elastic Load Balancing with an SSL listener that terminates the back-end connection to the application. (Needs to be published to internet)
    3. 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)
    4. 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)
  5. 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]
    1. End-to-end protection of data in transit
    2. End-to-end Identity authentication
    3. Data encryption across the Internet
    4. Protection of data in transit over the Internet
    5. Peer identity authentication between VPN gateway and customer gateway
    6. Data integrity protection across the Internet
  6. 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]
    1. 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)
    2. 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)
    3. 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)
    4. 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)

References

AWS VPC NAT – NAT Gateway

NAT Gateway High Availability

AWS NAT

  • 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
    • NAT Instance

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.
  • Public NAT gateway is associated with One Elastic IP address which cannot be disassociated after its creation.
  • Each NAT gateway is created in a specific Availability Zone and implemented with redundancy in that zone.
  • A NAT gateway supports the TCP, UDP, and ICMP protocols.
  • 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 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.
  • A NAT gateway only passes traffic from an instance in a private subnet to the internet.

NAT Gateway High Availability

NAT Gateway vs NAT Instance

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.
  1. 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?
    1. Attaching a second Elastic Network interface (ENI) to the NAT instance, and placing it in the private subnet
    2. Attaching an Elastic IP address to the instance in the private subnet
    3. Attaching a second Elastic Network Interface (ENI) to the instance in the private subnet, and placing it in the public subnet
    4. Disabling the Source/Destination Check attribute on the NAT instance
  2. 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?
    1. Enable Source/Destination Check on the private Instances.
    2. Enable Source/Destination Check on the NAT instance.
    3. Disable Source/Destination Check on the private instances
    4. Disable Source/Destination Check on the NAT instance
  3. 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?
    1. For Inbound allow Source: 20.0.1.0/24 on port 80
    2. For Outbound allow Destination: 0.0.0.0/0 on port 80
    3. For Inbound allow Source: 20.0.0.0/24 on port 80 (Refer NATSG)
    4. For Outbound allow Destination: 0.0.0.0/0 on port 443
  4. 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?
    1. Route payment requests through two NAT instances setup for High Availability and whitelist the Elastic IP addresses attached to the NAT instances
    2. Whitelist the VPC Internet Gateway Public IP and route payment requests through the Internet Gateway. (Internet gateway is only to route traffic)
    3. Whitelist the ELB IP addresses and route payment requests from the Application servers through the ELB. (ELB does not have a fixed IP address)
    4. 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)

AWS Network Connectivity Options

AWS Network Connectivity Options

Internet Gateway

  • provides Internet connectivity to VPC
  • 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.
  • supports IPv4 and IPv6 traffic.

NAT Gateway

  • 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.
  • Private NAT gateway allows instances in private subnets to connect to other VPCs or the on-premises network.

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 that
  • 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 Endpoints

  • 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 two 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.

VPC Private LinksAWS Private Links

  • 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 Peering

  • 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
  • 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

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).

Transit VPC

  • 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. Can be used to provide shared services for VPC Endpoints, Direct Connect connection, etc.
    • supports network address translation between overlapping network ranges.
    • supports vendor functionality around advanced security (layer 7 firewall/Intrusion Prevention System (IPS)/Intrusion Detection System (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

Transit Gateway

Transit Gateway

  • 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 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

Hybrid Connectivity

AWS Network Connectivity Decision Tree

Virtual Private Network (VPN)

VPC Managed VPN Connection
  • 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 Managed VPN only provides Site-to-Site VPN connectivity. It does not provide Point-to-Site VPC connectivity for e.g. from Mobile
  • 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 Managed 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.

 

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
  • Software VPNs, with the above design, introduces a single point of failure and needs to be handled.

Direct Connect – DX

  • 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 1G or 10G physical Ethernet connection that an AWS Direct Connect Partner provisions on behalf of a customer.
  • 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

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.

Direct Connect Gateway

  • is a globally available resource to enable connections to multiple VPCs across different regions or AWS accounts.
  • allows you to connect an AWS Direct Connect connection to one or more VPCs in the account that are located in the same or different regions
  • allows connecting any participating VPCs from one private VIF, reducing Direct Connect management.
  • can be created in any public region and accessed from all other public regions
  • can also access the public resources in any AWS Region using a public virtual interface.

References