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High Lights- 3

Launch Templates and Tenancy​

  • A launch template specifies instance configuration (AMI ID, instance type, key pair, security groups, etc.).
  • Default tenancy: shared.
  • Tenancy behavior:
    • Launch Template: shared, VPC: dedicated → dedicated tenancy
    • Launch Template: dedicated, VPC: default → dedicated tenancy

EC2 Tenancy Options​

  • By default, Amazon EC2 instances run on shared tenancy.
  • Dedicated Instances:
    • Run on hardware dedicated to one customer.
    • Isolated across AWS accounts but can share hardware across instances within same account.
  • Dedicated Hosts:
    • Full control over instance placement.
    • Visibility into physical server.

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EC2 Spot Instances​

  • Spot Instance = unused EC2 at reduced price.
  • Pricing is determined by long-term demand/supply in each AZ.
  • Spot Instance request types:
    • One-time
    • Persistent
  • Persistent requests reopen after interruption.
    • Spot Fleets maintain target capacity by launching replacements.
    • Canceling requests:
      • May or may not terminate instance depending on config.

EC2 Recovery​

  • Recover impaired EC2 instance using CloudWatch alarms.
  • Recovery applies to hardware failure or AWS-repairable issues.
  • Preserves:
    • Instance ID
    • Private & Elastic IPs
    • Metadata
  • If instance is in a placement group, recovery remains within group.
  • Note: Data in memory is lost.

FSx for Lustre​

  • Use FSx for Lustre with Scratch File System for:
    • Temporary storage
    • Short-term data processing
  • No replication, non-persistent if a file server fails.
  • Up to 6× burst throughput of baseline 200 MBps/TiB.

Amazon Redshift​

  • Amazon Redshift is a fully managed petabyte-scale data warehouse in the cloud.
  • Can be a target for data migration from other databases.

Route 53: Alias vs CNAME​

  • Amazon Route 53:
    • No charge for alias queries, but charges for CNAME.
    • Alias → AWS resources only (S3, CloudFront, same hosted zone).
    • CNAME → Any DNS record.
  • At zone apex (covid19survey.com):
    • Cannot create CNAME
    • Can create alias (e.g., point to www.covid19survey.com)

Internet Gateway​

  • Internet Gateway:
    • Acts as route target for internet-bound traffic.
    • Performs network address translation (NAT) for public IPv4 instances.

Amazon SQS Polling​

  • Amazon SQS supports:
    • Short polling: immediate response, may be empty.
    • Long polling: waits for messages up to a timeout.


  • Long polling makes it inexpensive to retrieve messages, reducing cost and empty receives.

AWS CloudFormation StackSets​

  • StackSet = CloudFormation + multi-account + multi-region.
  • Uses one template from admin account.
  • Provisions into target accounts/org units across regions.

Elastic Load Balancer: Connection Draining​

  • Elastic Load Balancing:
    • Uses connection draining for:
      • De-registering or unhealthy instances.
      • Preserves existing connections until timeout (1–3600s, default: 300s).
    • After timeout, force-closes remaining connections.

DynamoDB Global Tables​

  • Active-active configuration in DynamoDB global tables:
    • No failover – data is written regionally and replicated.
    • More expensive than Aurora Global Database.

VPC Sharing​

  • VPC sharing via Resource Access Manager (RAM):
    • Allows multiple accounts to deploy resources in a shared VPC.
    • Owner shares subnets (not VPC itself) with org participants.

Elastic Fabric Adapter (EFA)​

  • Elastic Fabric Adapter (EFA):
    • Enhances HPC and ML inter-instance communication.
    • Adds OS-bypass interface to ENA features.
    • User-space apps can access transport directly for performance.