AWS Certification Exam Cheat Sheet

AWS Certification Exam Cheat Sheet

AWS Certification Exams cover a lot of topics and a wide range of services with minute details for features, patterns, anti patterns and their integration with other services. This blog post is just to have a quick summary of all the services and key points for a quick glance before you appear for the exam

AWS Region, AZs, Edge locations

  • Each region is a separate geographic area, completely independent, isolated from the other regions & helps achieve the greatest possible fault tolerance and stability
  • Communication between regions is across the public Internet
  • Each region has multiple Availability Zones
  • Each AZ is physically isolated, geographically separated from each other and designed as an independent failure zone
  • AZs are connected with low-latency private links (not public internet)
  • Edge locations are locations maintained by AWS through a worldwide network of data centers for the distribution of content to reduce latency.

AWS Services

Consolidate Billing

  • Paying account with multiple linked accounts
  • Paying account is independent and should be only used for billing purpose
  • Paying account cannot access resources of other accounts unless given exclusively access through Cross Account roles
  • All linked accounts are independent and soft limit of 20
  • One bill per AWS account
  • provides Volume pricing discount for usage across the accounts
  • allows unused Reserved Instances to be applied across the group
  • Free tier is not applicable across the accounts

Tags & Resource Groups

  • are metadata, specified as key/value pairs with the AWS resources
  • are for labelling purposes and helps managing, organizing resources
  • can be inherited when created resources created from Auto Scaling, Cloud Formation, Elastic Beanstalk etc
  • can be used for
    • Cost allocation to categorize and track the AWS costs
    • Conditional Access Control policy to define permission to allow or deny access on resources based on tags
  • Resource Group is a collection of resources that share one or more tags

IDS/IPS

  • Promiscuous mode is not allowed, as AWS and Hypervisor will not deliver any traffic to instances this is not specifically addressed to the instance
  • IDS/IPS strategies
    • Host Based Firewall – Forward Deployed IDS where the IDS itself is installed on the instances
    • Host Based Firewall – Traffic Replication where IDS agents installed on instances which send/duplicate the data to a centralized IDS system
    • In-Line Firewall – Inbound IDS/IPS Tier (like a WAF configuration) which identifies and drops suspect packets

DDOS Mitigation

  • Minimize the Attack surface
    • use ELB/CloudFront/Route 53 to distribute load
    • maintain resources in private subnets and use Bastion servers
  • Scale to absorb the attack
    • scaling helps buy time to analyze and respond to an attack
    • auto scaling with ELB to handle increase in load to help absorb attacks
    • CloudFront, Route 53 inherently scales as per the demand
  • Safeguard exposed resources
    • user Route 53 for aliases to hide source IPs and Private DNS
    • use CloudFront geo restriction and Origin Access Identity
    • use WAF as part of the infrastructure
  • Learn normal behavior (IDS/WAF)
    • analyze and benchmark to define rules on normal behavior
    • use CloudWatch
  • Create a plan for attacks

AWS Services Region, AZ, Subnet VPC limitations

  • Services like IAM (user, role, group, SSL certificate), Route 53, STS are Global and available across regions
  • All other AWS services are limited to Region or within Region and do not exclusively copy data across regions unless configured
  • AMI are limited to region and need to be copied over to other region
  • EBS volumes are limited to the Availability Zone, and can be migrated by creating snapshots and copying them to another region
  • Reserved instances are limited to Availability Zone and cannot be migrated to another region
  • RDS instances are limited to the region and can be recreated in a different region by either using snapshots or promoting a Read Replica
  • Placement groups are limited to the Availability Zone
  • S3 data is replicated within the region and can be move to another region using cross region replication
  • DynamoDB maintains data within the region can be replicated to another region using DynamoDB cross region replication (using DynamoDB streams) or Data Pipeline using EMR (old method)
  • Redshift Cluster span within an Availability Zone only, and can be created in other AZ using snapshots

Disaster Recovery Whitepaper

  • RTO is the time it takes after a disruption to restore a business process to its service level and RPO acceptable amount of data loss measured in time before the disaster occurs
  • Techniques (RTO & RPO reduces and the Cost goes up as we go down)
    • Backup & Restore – Data is backed up and restored, within nothing running
    • Pilot light – Only minimal critical service like RDS is running and rest of the services can be recreated and scaled during recovery
    • Warm Standby – Fully functional site with minimal configuration is available and can be scaled during recovery
    • Multi-Site – Fully functional site with identical configuration is available and processes the load
  • Services
    • Region and AZ to launch services across multiple facilities
    • EC2 instances with the ability to scale and launch across AZs
    • EBS with Snapshot to recreate volumes in different AZ or region
    • AMI to quickly launch preconfigured EC2 instances
    • ELB and Auto Scaling to scale and launch instances across AZs
    • VPC to create private, isolated section
    • Elastic IP address as static IP address
    • ENI with pre allocated Mac Address
    • Route 53 is highly available and scalable DNS service to distribute traffic across EC2 instances and ELB in different AZs and regions
    • Direct Connect for speed data transfer (takes time to setup and expensive then VPN)
    • S3 and Glacier (with RTO of 3-5 hours) provides durable storage
    • RDS snapshots and Multi AZ support and Read Replicas across regions
    • DynamoDB with cross region replication
    • Redshift snapshots to recreate the cluster
    • Storage Gateway to backup the data in AWS
    • Import/Export to move large amount of data to AWS (if internet speed is the bottleneck)
    • CloudFormation, Elastic Beanstalk and Opsworks as orchestration tools for automation and recreate the infrastructure

 

AWS Certification – Analytics Services – Cheat Sheet

Data Pipeline

  • orchestration service that helps define data-driven workflows to automate and schedule regular data movement and data processing activities
  • integrates with on-premises and cloud-based storage systems
  • allows scheduling, retry, and failure logic for the workflows

EMR

  • is a web service that utilizes a hosted Hadoop framework running on the web-scale infrastructure of EC2 and S3
  • launches all nodes for a given cluster in the same Availability Zone, which improves performance as it provides higher data access rate
  • seamlessly supports Reserved, On-Demand and Spot Instances
  • consists of Master Node for management and Slave nodes, which consists of Core nodes holding data and Task nodes for performing tasks only
  • is fault tolerant for slave node failures and continues job execution if a slave node goes down
  • does not automatically provision another node to take over failed slaves
  • supports Persistent and Transient cluster types
    • Persistent which continue to run
    • Transient which terminates once the job steps are completed
  • supports EMRFS which allows S3 to be used as a durable HA data storage

Kinesis

  • enables real-time processing of streaming data at massive scale
  • provides ordering of records, as well as the ability to read and/or replay records in the same order to multiple Kinesis applications
  • data is replicated across three data centers within a region and preserved for 24 hours, by default and can be extended to 7 days
  • streams can be scaled using multiple shards, based on the partition key, with each shard providing the capacity of 1MB/sec data input and 2MB/sec data output with 1000 PUT requests per second
  • Kinesis vs SQS
    • real-time processing of streaming big data vs reliable, highly scalable hosted queue for storing messages
    • ordered records, as well as the ability to read and/or replay records in the same order vs no guarantee on data ordering (with the standard queues before the FIFO queue feature was released)
    • data storage up to 24 hours, extended to 7 days vs up to 4 days, can be configured from 1 minute to 14 days but cleared if deleted by the consumer
    • supports multiple consumers vs single consumer at a time and requires multiple queues to deliver message to multiple consumers

AWS Certification – Application Services – Cheat Sheet

SQS

  • extremely scalable queue service and potentially handles millions of messages
  • helps build fault tolerant, distributed loosely coupled applications
  • stores copies of the messages on multiple servers for redundancy and high availability
  • guarantees At-Least-Once Delivery, but does not guarantee Exact One Time Delivery which might result in duplicate messages (Not true anymore with the introduction of FIFO queues)
  • does not maintain or guarantee message order, and if needed sequencing information needs to be added to the message itself (Not true anymore with the introduction of FIFO queues)
  • supports multiple readers and writers interacting with the same queue as the same time
  • holds message for 4 days, by default, and can be changed from 1 min – 14 days after which the message is deleted
  • message needs to be explicitly deleted by the consumer once processed
  • allows send, receive and delete batching which helps club up to 10 messages in a single batch while charging price for a single message
  • handles visibility of the message to multiple consumers using Visibility Timeout, where the message once read by a consumer is not visible to the other consumers till the timeout occurs
  • can handle load and performance requirements by scaling the worker instances as the demand changes (Job Observer pattern)
  • message sample allowing short and long polling
    • returns immediately vs waits for fixed time for e.g. 20 secs
    • might not return all messages as it samples a subset of servers vs returns all available messages
    • repetitive vs helps save cost with long connection
  • supports delay queues to make messages available after a certain delay, can you used to differentiate from priority queues
  • supports dead letter queues, to redirect messages which failed to process after certain attempts instead of being processed repeatedly
  • Design Patterns
    • Job Observer Pattern can help coordinate number of EC2 instances with number of job requests (Queue Size) automatically thus Improving cost effectiveness and performance
    • Priority Queue Pattern can be used to setup different queues with different handling either by delayed queues or low scaling capacity for handling messages in lower priority queues

SNS

  • delivery or sending of messages to subscribing endpoints or clients
  • publisher-subscriber model
  • Producers and Consumers communicate asynchronously with subscribers by producing and sending a message to a topic
  • supports Email (plain or JSON), HTTP/HTTPS, SMS, SQS
  • supports Mobile Push Notifications to push notifications directly to mobile devices with services like Amazon Device Messaging (ADM), Apple Push Notification Service (APNS), Google Cloud Messaging (GCM) etc. supported
  • order is not guaranteed and No recall available
  • integrated with Lambda to invoke functions on notifications
  • for Email notifications, use SNS or SES directly, SQS does not work

SWF

  • orchestration service to coordinate work across distributed components
  • helps define tasks, stores, assigns tasks to workers, define logic, tracks and monitors the task and maintains workflow state in a durable fashion
  • helps define tasks which can be executed on AWS cloud or on-premises
  • helps coordinating tasks across the application which involves managing intertask dependencies, scheduling, and concurrency in accordance with the logical flow of the application
  • supports built-in retries, timeouts and logging
  • supports manual tasks
  • Characteristics
    • deliver exactly once
    • uses long polling, which reduces number of polls without results
    • Visibility of task state via API
    • Timers, signals, markers, child workflows
    • supports versioning
    • keeps workflow history for a user-specified time
  • AWS SWF vs AWS SQS
    • task-oriented vs message-oriented
    • track of all tasks and events vs needs custom handling

SES

  • highly scalable and cost-effective email service
  • uses content filtering technologies to scan outgoing emails to check standards and email content for spam and malware
  • supports full fledged emails to be sent as compared to SNS where only the message is sent in Email
  • ideal for sending bulk emails at scale
  • guarantees first hop
  • eliminates the need to support custom software or applications to do heavy lifting of email transport

AWS Certification – Database Services – Cheat Sheet

RDS

  • provides Relational Database service
  • supports MySQL, MariaDB, PostgreSQL, Oracle, Microsoft SQL Server, and the new, MySQL-compatible Amazon Aurora DB engine
  • as it is a managed service, shell (root ssh) access is not provided
  • manages backups, software patching, automatic failure detection, and recovery
  • supports use initiated manual backups and snapshots
  • daily automated backups with database transaction logs enables Point in Time recovery up to the last five minutes of database usage
  • snapshots are user-initiated storage volume snapshot of DB instance, backing up the entire DB instance and not just individual databases that can be restored as a independent RDS instance
  • support encryption at rest using KMS as well as encryption in transit using SSL endpoints
  • for encrypted database
    • logs, snapshots, backups, read replicas are all encrypted as well
    • cross region replicas and snapshots does not work across region
  • Multi-AZ deployment
    • provides high availability and automatic failover support and is NOT a scaling solution
    • maintains a synchronous standby replica in a different AZ
    • transaction success is returned only if the commit is successful both on the primary and the standby DB
    • Oracle, PostgreSQL, MySQL, and MariaDB DB instances use Amazon technology, while SQL Server DB instances use SQL Server Mirroring
    • snapshots and backups are taken from standby & eliminate I/O freezes
    • during automatic failover, its seamless and RDS switches to the standby instance and updates the DNS record to point to standby
    • failover can be forced with the Reboot with failover option
  • Read Replicas
    • uses the PostgreSQL, MySQL, and MariaDB DB engines’ built-in replication functionality to create a separate Read Only instance
    • updates are asynchronously copied to the Read Replica, and data might be stale
    • can help scale applications and reduce read only load 
    • requires automatic backups enabled
    • replicates all databases in the source DB instance
    • for disaster recovery, can be promoted to a full fledged database
    • can be created in a different region for MySQL, Postgres and MariaDB, for disaster recovery, migration and low latency across regions
  • RDS does not support all the features of underlying databases, and if required the database instance can be launched on an EC2 instance
  • RMAN (Recovery Manager) can be used for Oracles backup and recovery when running on an EC2 instance

DynamoDB

  • fully managed NoSQL database service
  • synchronously replicates data across three facilities in an AWS Region, giving high availability and data durability
  • runs exclusively on SSDs to provide high I/O performance
  • provides provisioned table reads and writes
  • automatically partitions, reallocates and re-partitions the data and provisions additional server capacity as data or throughput changes
  • provides Eventually consistent (by default) or Strongly Consistent option to be specified during an read operation
  • creates and maintains indexes for the primary key attributes for efficient access of data in the table
  • supports secondary indexes
    • allows querying attributes other then the primary key attributes without impacting performance.
    • are automatically maintained as sparse objects
  • Local vs Global secondary index
    • shares partition key + different sort key vs different partition + sort key
    • search limited to partition vs across all partition
    • unique attributes vs non unique attributes
    • linked to the base table vs independent separate index
    • only created during the base table creation vs can be created later
    • cannot be deleted after creation vs can be deleted
    • consumes provisioned throughput capacity of the base table vs independent throughput
    • returns all attributes for item vs only projected attributes
    • Eventually or Strongly vs Only Eventually consistent reads
    • size limited to 10Gb per partition vs unlimited
  • supports cross region replication using DynamoDB streams which leverages Kinesis and provides time-ordered sequence of item-level changes and can help for lower RPO, lower RTO disaster recovery
  • Data Pipeline jobs with EMR can be used for disaster recovery with higher RPO, lower RTO requirements
  • supports triggers to allow execution of custom actions or notifications based on item-level updates

ElastiCache

  • managed web service that provides in-memory caching to deploy and run Memcached or Redis protocol-compliant cache clusters
  • ElastiCache with Redis,
    • like RDS, supports Multi-AZ, Read Replicas and Snapshots
    • Read Replicas are created across AZ within same region using Redis’s asynchronous replication technology
    • Multi-AZ differs from RDS as there is no standby, but if the primary goes down a Read Replica is promoted as primary
    • Read Replicas cannot span across regions, as RDS supports
    • cannot be scaled out and if scaled up cannot be scaled down
    • allows snapshots for backup and restore
    • AOF can be enabled for recovery scenarios, to recover the data in case the node fails or service crashes. But it does not help in case the underlying hardware fails
    • Enabling Redis Multi-AZ as a Better Approach to Fault Tolerance
  • ElastiCache with Memcached
    • can be scaled up by increasing size and scaled out by adding nodes
    • nodes can span across multiple AZs within the same region
    • cached data is spread across the nodes, and a node failure will always result in some data loss from the cluster
    • supports auto discovery
    • every node should be homogenous and of same instance type
  • ElastiCache Redis vs Memcached
    • complex data objects vs simple key value storage
    • persistent vs non persistent, pure caching
    • automatic failover with Multi-AZ vs Multi-AZ not supported
    • scaling using Read Replicas vs using multiple nodes
    • backup & restore supported vs not supported
  • can be used state management to keep the web application stateless

Redshift

  • fully managed, fast and powerful, petabyte scale data warehouse service
  • uses replication and continuous backups to enhance availability and improve data durability and can automatically recover from node and component failures
  • provides Massive Parallel Processing (MPP) by distributing & parallelizing queries across multiple physical resources
  • columnar data storage improving query performance and allowing advance compression techniques
  • only supports Single-AZ deployments and the nodes are available within the same AZ, if the AZ supports Redshift clusters
  • spot instances are NOT an option

AWS Certification – Networking Services – Cheat Sheet

VPC

  • helps define a logically isolated dedicated virtual network within the AWS
  • provides control of IP addressing using CIDR block from a minimum of /28 to maximum of /16 block size
  • Components
    • Internet gateway (IGW) provides access to the Internet
    • Virtual gateway (VGW) provides access to on-premises data center through VPN and Direct Connect connections
    • VPC can have only one IGW and VGW
    • Route tables determine where network traffic from subnet is directed
    • Ability to create subnet with VPC CIDR block
    • A Network Address Translation (NAT) server provides outbound Internet access for EC2 instances in private subnets
    • Elastic IP addresses are static, persistent public IP addresses
    • Instances launched in the VPC will have a Private IP address and can have a Public or a Elastic IP address associated with it
    • Security Groups and NACLs help define security
    • Flow logs – Capture information about the IP traffic going to and from network interfaces in your VPC
  • allows Tenancy option for instances
    • shared, by default, allows instances to be launched on shared tenancy
    • dedicated allows instances to be launched on a dedicated hardware
  • NAT
    • allows internet access to instances in private subnet
    • performs the function of both address translation and port address translation (PAT)
    • needs source/destination check flag to be disabled as it is not actual destination of  the traffic
    • NAT gateway is a AWS managed NAT service that provides better availability, higher bandwidth, and requires less administrative effort
  • Route Tables
    • defines rules, termed as routes, which determine where network traffic from the subnet would be routed
    • Each VPC has a Main Route table, and can have multiple custom route tables created
    • 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
  • Subnets
    • map to AZs and do not span across AZs
    • have a CIDR range that is a portion of the whole VPC.
    • CIDR ranges cannot overlap between subnets within the VPC.
    • AWS reserves 5 IP addresses in each subnet – first 4 and last one
    • Each subnet is associated with a route table which define its behavior
      • Public subnets – inbound/outbound Internet connectivity via IGW
      • Private subnets – outbound Internet connectivity via an NAT or VGW
      • Protected subnets – no outbound connectivity and used for regulated workloads
  • Elastic Network Interface (ENI)
    • a default ENI, eth0, is attached to an instance which cannot be detached with one or more secondary detachable ENIs (eth1-ethn)
    • has primary private, one or more secondary private, public, Elastic IP address, security groups, MAC address and source/destination check flag attributes associated
    • AN ENI in one subnet can be attached to an instance in the same or another subnet, in the same AZ and the same VPC
    • Security group membership of an ENI can be changed
    • with pre allocated Mac Address can be used for applications with special licensing requirements
  • Security Groups vs Network Access Control Lists
    • Stateful vs Stateless
    • At instance level vs At subnet level
    • Only allows Allow rule vs Allows both Allow and Deny rules
    • Evaluated as a Whole vs Evaluated in defined Order
  • Elastic IP
    • is a static IP address designed for dynamic cloud computing.
    • is associated with AWS account, and not a particular instance
    • can be remapped from one instance to an other instance
    • is charged for non usage, if not linked for any instance or instance associated is in stopped state
  • VPC Peering
    • allows routing of traffic between the peer VPCs using private IP addresses and no IGW or VGW required
    • No single point of failure and bandwidth bottlenecks
    • cannot span across regions
    • IP space or CIDR blocks cannot overlap
    • cannot be transitive, one-to-one relationship between two VPC
    • Only one between any two VPCs and have to be explicitly peered
    • Private DNS values cannot be resolved
    • Security groups from peered VPC cannot be referred for ingress and egress rules in security group, use CIDR block instead
  • VPC Endpoints
    • enables creation of a private connection between VPC and another AWS service (currently only S3) using its private IP address
    • does not require a public IP address, access over the Internet, NAT device, a VPN connection or AWS Direct Connect
    • traffic between VPC & AWS service does not leave the Amazon network
    • do not support cross-region requests
    • cannot be extended out of a VPC i.e. resources across the VPN, VPC peering, AWS Direct Connect connection cannot use the endpoint

Direct Connect & VPN

  • VPN
    • provide secure IPSec connections from on-premise computers or services to AWS over the Internet
    • is quick to setup, is cheap however it depends on the Internet speed
  • Direct Connect
    • is a network service that provides an alternative to using Internet to utilize AWS services by using private dedicated network connection
    • provides Virtual Interfaces
      • Private VIF to access instances within an VPC via VGW
      • Public VIF to access non VPC services
    • requires time to setup probably months, and should not be considered as an option if turnaround time is less
    • does not provide redundancy, use either second direct connection or IPSec VPN connection
    • Virtual Private Gateway is on the AWS side and Customer Gateway is on the Customer side
    • route propagation is enabled on VGW and not on CGW
  • Direct Connect vs VPN IPSec
    • Expensive to Setup and Takes time vs Cheap & Immediate
    • Dedicated private connections vs Internet
    • Reduced data transfer rate vs Internet data transfer cost
    • Consistent performance vs Internet inherent variability
    • Do not provide Redundancy vs Provides Redundancy

Route 53

  • Highly available and scalable DNS & Domain Registration Service
  • Reliable and cost-effective way to route end users to Internet applications
  • Supports multi-region and backup architectures for High availability. ELB , limited to region, does not support multi region HA architecture
  • supports private Intranet facing DNS service
  • internal resource record sets only work for requests originating from within the VPC and currently cannot extend to on-premise
  • Global propagation of any changes made to the DN records within ~ 1min
  • Route 53 to create an alias resource record set that points to ELB, S3, CloudFront. An alias resource record set is an Route 53 extension to DNS. It’s similar to a CNAME resource record set, but supports both for root domain – zone apex  e.g. example.com, and for subdomains for e.g. www.example.com.
  • CNAME resource record sets can be created only for subdomains and cannot be mapped to the zone apex record
  • Routing policy
    • Simple routing – simple round robin policy
    • Weighted round robin – assign weights to resource records sets to specify the proportion for e.g. 80%:20%
    • Latency based routing – helps improve global applications as request are sent to server from the location with minimal latency, is based on the latency and cannot guarantee users from the same geographic will be served from the same location for any compliance reasons
    • Geolocation routing – Specify geographic locations by continent, country, state limited to US, is based on IP accuracy
    • Failover routing – failover to a backup site if the primary site fails and becomes unreachable
  • Weighted, Latency and Geolocation can be used for Active-Active while Failover routing can be used for Active-Passive multi region architecture

AWS Certification – Management Tools – Cheat Sheet

CloudFormation

  • gives developers and systems administrators an easy way to create and manage a collection of related AWS resources
  • Resources can be updated, deleted and modified in a orderly, controlled and predictable fashion, in effect applying version control to the AWS infrastructure as code done for software code
  • CloudFormation Template is an architectural diagram, in JSON format, and Stack is the end result of that diagram, which is actually provisioned
  • template can be used to set up the resources consistently and repeatedly over and over across multiple regions and consists of
    • List of AWS resources and their configuration values
    • An optional template file format version number
    • An optional list of template parameters (input values supplied at stack creation time)
    • An optional list of output values like public IP address using the Fn::GetAtt function
    • An optional list of data tables used to lookup static configuration values for e.g., AMI names per AZ
  • supports Chef & Puppet Integration to deploy and configure right down the the application layer
  • supports Bootstrap scripts to install packages, files and services on the EC2 instances by simple describing them in the CF template
  • automatic rollback on error feature is enabled, by default, which will cause all the AWS resources that CF created successfully for a stack up to the point where an error occurred to be deleted
  • provides a WaitCondition resource to block the creation of other resources until a completion signal is received from an external source
  • allows DeletionPolicy attribute to be defined for resources in the template
    • retain to preserve resources like S3 even after stack deletion
    • snapshot to backup resources like RDS after stack deletion
  • DependsOn attribute to specify that the creation of a specific resource follows another
  • Service role is an IAM role that allows AWS CloudFormation to make calls to resources in a stack on the user’s behalf
  • support Nested stacks that can separate out reusable, common components and create dedicated templates to mix and match different templates but use nested stacks to create a single, unified stack

Elastic BeanStalk

  • makes it easier for developers to quickly deploy and manage applications in the AWS cloud.
  • automatically handles the deployment details of capacity provisioning, load balancing, auto-scaling and application health monitoring
  • CloudFormation supports ElasticBeanstalk
  • provisions resources to support
    • a web application that handles HTTP(S) requests or
    • a web application that handles background-processing (worker) tasks
  • supports Out Of the Box
    • Apache Tomcat for Java applications
    • Apache HTTP Server for PHP applications
    • Apache HTTP server for Python applications
    • Nginx or Apache HTTP Server for Node.js applications
    • Passenger for Ruby applications
    • MicroSoft IIS 7.5 for .Net applications
    • Single and Multi Container Docker
  • supports custom AMI to be used
  • is designed to support multiple running environments such as one for Dev, QA, Pre-Prod and Production.
  • supports versioning and stores and tracks application versions over time allowing easy rollback to prior version
  • can provision RDS DB instance and connectivity information is exposed to the application by environment variables, but is NOT recommended for production setup as the RDS is tied up with the Elastic Beanstalk lifecycle and if deleted, the RDS instance would be deleted as well

OpsWorks

  • is a configuration management service that helps to configure and operate applications in a cloud enterprise by using Chef
  • helps deploy and monitor applications in stacks with multiple layers
  • supports preconfigured layers for Applications, Databases, Load Balancers, Caching
  • OpsWorks Stacks features is a set of lifecycle events – Setup, Configure, Deploy, Undeploy, and Shutdown – which automatically runs specified set of recipes at the appropriate time on each instance
  • Layers depend on Chef recipes to handle tasks such as installing packages on instances, deploying apps, running scripts, and so on
  • OpsWorks Stacks runs the recipes for each layer, even if the instance belongs to multiple layers
  • supports Auto Healing and Auto Scaling to monitor instance health, and provision new instances

CloudWatch

  • allows monitoring of AWS resources and applications in real time, collect and track pre configured or custom metrics and configure alarms to send notification or make resource changes based on defined rules
  • does not aggregate data across regions
  • stores the log data indefinitely, and the retention can be changed for each log group at any time
  • alarm history is stored for only 14 days
  • can be used an alternative to S3 to store logs with the ability to configure Alarms and generate metrics, however logs cannot be made public
  • Alarms exist only in the created region and the Alarm actions must reside in the same region as well

CloudTrail

  • records access to API calls for the AWS account made from AWS management console, SDKs, CLI and higher level AWS service
  • support many AWS services and tracks who did, from where, what & when
  • can be enabled per-region basis, a region can include global services (like IAM, STS etc), is applicable to all the supported services within that region
  • log files from different regions can be sent to the same S3 bucket
  • can be integrated with SNS to notify logs availability, CloudWatch logs log group for notifications when specific API events occur
  • call history enables security analysis, resource change tracking, trouble shooting and compliance auditing

AWS Certification – Security & Identity Services – Cheat Sheet

IAM

  • securely control access to AWS services and resources
  • helps create and manage user identities and grant permissions for those users to access AWS resources
  • helps create groups for multiple users with similar permissions
  • not appropriate for application authentication
  • is Global and does not need to be migrated to a different region
  • helps define Policies,
    • in JSON format
    • all permissions are implicitly denied by default
    • most restrictive policy wins
  • IAM Role
    • helps grants and delegate access to users and services without the need of creating permanent credentials
    • IAM users or AWS services can assume a role to obtain temporary security credentials that can be used to make AWS API calls
    • needs Trust policy to define who and Permission policy to define what the user or service can access
    • used with Security Token Service (STS), a lightweight web service that provides temporary, limited privilege credentials for IAM users or for authenticated federated users
    • IAM role scenarios
      • Service access for e.g. EC2 to access S3 or DynamoDB
      • Cross Account access for users
        • with user within the same account
        • with user within an AWS account owned the same owner
        • with user from a Third Party AWS account with External ID for enhanced security
      • Identity Providers & Federation
        • Web Identity Federation, where the user can be authenticated using external authentication Identity providers like Amazon, Google or any OpenId IdP using AssumeRoleWithWebIdentity
        • Identity Provider using SAML 2.0, where the user can be authenticated using on premises Active Directory, Open Ldap or any SAML 2.0 compliant IdP using AssumeRoleWithSAML
        • For other Identity Providers, use Identity Broker to authenticate and provide temporary Credentials using AssumeRole (recommended) or GetFederationToken
  • IAM Best Practices
    • Do not use Root account for anything other than billing
    • Create Individual IAM users
    • Use groups to assign permissions to IAM users
    • Grant least privilege
    • Use IAM roles for applications on EC2
    • Delegate using roles instead of sharing credentials
    • Rotate credentials regularly
    • Use Policy conditions for increased granularity
    • Use CloudTrail to keep a history of activity
    • Enforce a strong IAM password policy for IAM users
    • Remove all unused users and credentials

CloudHSM

  • provides secure cryptographic key storage to customers by making hardware security modules (HSMs) available in the AWS cloud
  • single tenant, dedicated physical device to securely generate, store, and manage cryptographic keys used for data encryption
  • are inside the VPC (not EC2-classic) & isolated from the rest of the network
  • can use VPC peering to connect to CloudHSM from multiple VPCs
  • integrated with Amazon Redshift and Amazon RDS for Oracle
  • EBS volume encryption, S3 object encryption and key management can be done with CloudHSM but requires custom application scripting
  • is NOT fault tolerant and would need to build a cluster as if one fails all the keys are lost
  • expensive, prefer AWS Key Management Service (KMS) if cost is a criteria

AWS Directory Services

  • gives applications in AWS access to Active Directory services
  • different from SAML + AD, where the access is granted to AWS services through Temporary Credentials
  • Simple AD
    • least expensive but does not support Microsoft AD advance features
    • provides a Samba 4 Microsoft Active Directory compatible standalone directory service on AWS
    • No single point of Authentication or Authorization, as a separate copy is maintained
    • trust relationships cannot be setup between Simple AD and other Active Directory domains
    • Don’t use it, if the requirement is to leverage access and control through centralized authentication service
  • AD Connector
    • acts just as an hosted proxy service for instances in AWS to connect to on-premises Active Directory
    • enables consistent enforcement of existing security policies, such as password expiration, password history, and account lockouts, whether users are accessing resources on-premises or in the AWS cloud
    • needs VPN connectivity (or Direct Connect)
    • integrates with existing RADIUS-based MFA solutions to enabled multi-factor authentication
    • does not cache data which might lead to latency
  • Read-only Domain Controllers (RODCs)
    • works out as a Read-only Active Directory
    • holds a copy of the Active Directory Domain Service (AD DS) database and respond to authentication requests
    • they cannot be written to and are typically deployed in locations where physical security cannot be guaranteed
    • helps maintain a single point to authentication & authorization controls, however needs to be synced
  • Writable Domain Controllers
    • are expensive to setup
    • operate in a multi-master model; changes can be made on any writable server in the forest, and those changes are replicated to servers throughout the entire forest

AWS WAF

  • is a web application firewall that helps monitor the HTTP/HTTPS requests forwarded to CloudFront and allows controlling access to the content.
  • helps define Web ACLs, which is a combination of Rules, which is a combinations of Conditions and Action to block or allow
  • Third Party WAF
    • act as filters that apply a set of rules to web traffic to cover exploits like XSS and SQL injection and also help build resiliency against DDoS by mitigating HTTP GET or POST floods
    • WAF provides a lot of features like OWASP Top 10, HTTP rate limiting, Whitelist or blacklist, inspect and identify requests with abnormal patterns, CAPTCHA etc
    • a WAF sandwich pattern can be implemented where an autoscaled WAF sits between the Internet and Internal Load Balancer

 

AWS Certification – Compute Services – Cheat Sheet

EC2

  • provides scalable computing capacity
  • Features
    • Virtual computing environments, known as EC2 instances
    • Preconfigured templates for EC2 instances, known as Amazon Machine Images (AMIs), that package the bits needed for the server (including the operating system and additional software)
    • Various configurations of CPU, memory, storage, and networking capacity for your instances, known as Instance types
    • Secure login information for your instances using key pairs (public-private keys where private is kept by user)
    • Storage volumes for temporary data that’s deleted when you stop or terminate your instance, known as Instance store volumes
    • Persistent storage volumes for data using Elastic Block Store (EBS)
    • Multiple physical locations for your resources, such as instances and EBS volumes, known as Regions and Availability Zones
    • A firewall to specify the protocols, ports, and source IP ranges that can reach your instances using Security Groups
    • Static IP addresses, known as Elastic IP addresses
    • Metadata, known as tags, can be created and assigned to EC2 resources
    • Virtual networks that are logically isolated from the rest of the AWS cloud, and can optionally connect to on premises network, known as Virtual private clouds (VPCs)
  • Amazon Machine Image
    • template from which EC2 instances can be launched quickly
    • does NOT span across across regions, and needs to be copied
    • can be shared with other specific AWS accounts or made public
  • Purchasing Option
    • On-Demand Instances
      • pay for instances and compute capacity that you use by the hour
      • with no long-term commitments or up-front payments
    • Reserved Instances
      • provides lower hourly running costs by providing a billing discount
      • capacity reservation that is applied to instances
      • suited if consistent, heavy, predictable usage
      • provides benefits with Consolidate Billing
      • can be modified to switch Availability Zones or the instance size within the same instance type, given the instance size footprint (Normalization factor) remains the same
      • pay for the entire term regardless of the usage, so if the question targets cost effective solution and answer mentions reserved instances are purchased & unused, it can be ignored
    • Spot Instances
      • cost-effective choice but does NOT guarantee availability
      • applications flexible in the timing when they can run and also able to handle interruption by storing the state externally
      • AWS will give a two minute warning if the instance is to be terminated to save any unsaved work
    • Dedicated Instances, is a tenancy option which enables instances to run in VPC on hardware that’s isolated, dedicated to a single customer
    • Light, Medium, and Heavy Utilization Reserved Instances are no longer available for purchase and were part of the Previous Generation AWS EC2 purchasing model
  • Enhanced Networking
    • results in higher bandwidth, higher packet per second (PPS) performance, lower latency, consistency, scalability and lower jitter
    • supported using Single Root I/O Virtualization (SR-IOV) only on supported instance types
    • is supported only with an VPC (not EC2 Classic), HVM virtualization type and available by default on Amazon AMI but can be installed on other AMIs as well
  • Placement Group
    • provide low latency, High Performance Computing via 10Gbps network
    • is a logical grouping on instances within a Single AZ
    • don’t span availability zones, can span multiple subnets but subnets must be in the same AZ
    • can span across peered VPCs for the same Availability Zones
    • existing instances cannot be moved into an existing placement group
    • for capacity errors, stop and start the instances in the placement group
    • use homogenous instance types which support enhanced networking and launch all the instances at once

EBS

Elastic Load Balancer & Auto Scaling

  • Elastic Load Balancer
    • Managed load balancing service and scales automatically
    • distributes incoming application traffic across multiple EC2 instances
    • is distributed system that is fault tolerant and actively monitored by AWS scales it as per the demand
    • are engineered to not be a single point of failure
    • need to Pre Warm ELB if the demand is expected to shoot especially during load testing
    • supports routing traffic to instances in multiple AZs in the same region
    • performs Health Checks to route traffic only to the healthy instances
    • support Listeners with HTTP, HTTPS, SSL, TCP protocols
    • has an associated IPv4 and dual stack DNS name
    • can offload the work of encryption and decryption (SSL termination) so that the EC2 instances can focus on their main work
    • supports Cross Zone load balancing to help route traffic evenly across all EC2 instances regardless of the AZs they reside in
    • to help identify the IP address of a client
      • supports Proxy Protocol header for TCP/SSL connections
      • supports X-Forward headers for HTTP/HTTPS connections
    • supports Stick Sessions (session affinity) to bind a user’s session to a specific application instance,
      • it is not fault tolerant, if an instance is lost the information is lost
      • requires HTTP/HTTPS listener and does not work with TCP
      • requires SSL termination on ELB as it users the headers
    • supports Connection draining to help complete the in-flight requests in case an instance is deregistered
    • For High Availability, it is recommended to attach one subnet per AZ for at least two AZs, even if the instances are in a single subnet.
    • cannot assign an Elastic IP address to an ELB
    • IPv4 & IPv6 support however VPC does not support IPv6
    • HTTPS listener does not support Client Side Certificate
    • for SSL termination at backend instances or support for Client Side Certificate use TCP for connections from the client to the ELB, use the SSL protocol for connections from the ELB to the back-end application, and deploy certificates on the back-end instances handling requests
    • supports a single SSL certificate, so for multiple SSL certificate multiple ELBs need to be created
  • Auto Scaling
    • ensures correct number of EC2 instances are always running to handle the load by scaling up or down automatically as demand changes
    • cannot span multiple regions.
    • attempts to distribute instances evenly between the AZs that are enabled for the Auto Scaling group
    • performs checks either using EC2 status checks or can use ELB health checks to determine the health of an instance and terminates the instance if unhealthy, to launch a new instance
    • can be scaled using manual scaling, scheduled scaling or demand based scaling
    • cooldown period helps ensure instances are not launched or terminated before the previous scaling activity takes effect to allow the newly launched instances to start handling traffic and reduce load
  • Auto Scaling & ELB can be used for High Availability and Redundancy by spanning Auto Scaling groups across multiple AZs within a region and then setting up ELB to distribute incoming traffic across those AZs
  • With Auto Scaling use ELB health check with the instances to ensure that traffic is routed only to the healthy instances