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

Few of the Topics are still WIP and planned to be added soon

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

 

6 thoughts on “AWS Certification Exam Cheat Sheet

  1. Hello Jayandera

    You are my role model. I am following your foot path as I completed two certifications (SA and Sys-Ops) earlier. Now I am also targeting professional. Your inputs are really helpful.

    If you post sample professional exam questions would be really helpful to me to aware where am I.

    Thanks
    K.Senthilkumar

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