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Difficulty: MediumData Transfer Cost Optimization

A company hosts a data processing workload on Amazon EC2 instances in private subnets across two Availability Zones (`eu-west-1a` and `eu-west-1b`) within a single VPC. The instances download regular updates from the internet and write approximately 12 TB12\text{ TB} of data monthly to Amazon DynamoDB. Currently, all outbound traffic from the private subnets routes through a single NAT Gateway located in a public subnet in `eu-west-1a`.

A SysOps administrator identifies high charges in the monthly bill for both NAT Gateway data processing and cross-Availability Zone data transfer.

Which combination of actions should the SysOps administrator take to minimize the data transfer costs? (Select TWO.)

  1. Create a Gateway VPC Endpoint for Amazon DynamoDB and associate it with the route tables of the private subnets.Answer
  2. Deploy a second NAT Gateway in a public subnet in `eu-west-1b` and update the route table of the private subnet in `eu-west-1b` to route internet-bound traffic through the new NAT Gateway.Answer
  3. C
    Create an Interface VPC Endpoint (AWS PrivateLink) for Amazon DynamoDB in both Availability Zones and update the route tables to point to the endpoints.
  4. D
    Create a Gateway VPC Endpoint for Amazon DynamoDB but leave the private subnet route tables unchanged to prevent connection dropouts.
  5. E
    Establish a VPC Peering connection between the subnets in `eu-west-1a` and `eu-west-1b` to route local internet traffic directly.

Answer

To optimize costs, the administrator should create a Gateway VPC Endpoint for Amazon DynamoDB and associate it with the private subnet route tables, and deploy a second NAT Gateway in the second Availability Zone to keep internet-bound traffic local to that zone.
The correct combination of actions consists of utilizing a Gateway VPC Endpoint for DynamoDB and deploying a second NAT Gateway. The Gateway Endpoint is free and routes the DynamoDB traffic privately, bypassing the NAT Gateway and eliminating its data processing fees. The second NAT Gateway prevents cross-Availability Zone traffic for internet-bound data from the second zone, reducing cross-AZ transfer costs.

Step-by-Step Solution

1
Divert high-volume DynamoDB traffic from the NAT Gateway.
Creating a Gateway VPC Endpoint for DynamoDB routes the 12 TB12\text{ TB} of monthly DynamoDB data directly over the AWS private network.
DynamoDB Gateway VPC Endpoints are free of charge, which avoids the NAT Gateway data processing fee ($0.045 per GB in most regions) for this massive volume of data.
2
Address the cross-Availability Zone data transfer charges for remaining internet traffic.
Deploying a second NAT Gateway in the second Availability Zone allows instances in that zone to route outbound internet traffic locally.
This eliminates the cross-AZ data transfer fees ($0.01 per GB in each direction) incurred when instances in one zone route traffic to a NAT Gateway in another zone.

Key Concept

Data transfer cost optimization in VPC environments involves routing traffic through free Gateway Endpoints for supported services (S3 and DynamoDB) and keeping internet-bound traffic local to the Availability Zone to avoid cross-AZ charges.
Estimated Time:2m 0s
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Topics

Data Transfer Cost Optimization

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