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Difficulty: EasyData Transfer Cost Optimization

An application running on Amazon EC2 instances in a private subnet frequently downloads large datasets from an Amazon S3 bucket in the same AWS Region. The subnet routes all outbound internet traffic through a NAT Gateway. A SysOps administrator notices high NAT Gateway data processing charges on the monthly AWS bill. Which action should the administrator take to eliminate these data processing charges in the most cost-effective manner?

  1. Create a Gateway VPC endpoint for Amazon S3 and associate it with the route table of the private subnet.Answer
  2. B
    Create a Gateway VPC endpoint for Amazon S3 but do not modify the route tables of the private subnet.
  3. C
    Provision an Interface VPC endpoint for Amazon S3 and update the application to use the endpoint's private DNS name.
  4. D
    Deploy a second NAT Gateway in a different Availability Zone and distribute the S3 traffic across both gateways.

Answer

Create a Gateway VPC endpoint for Amazon S3 and associate it with the route table of the private subnet.
The correct answer is to create a Gateway VPC endpoint for Amazon S3 and associate it with the route table of the private subnet. Gateway VPC endpoints for Amazon S3 are free and do not incur data processing or hourly charges. Associating the endpoint with the route table of the private subnet ensures that any outbound traffic destined for S3 bypasses the default NAT Gateway route and is directed to the endpoint instead, eliminating NAT Gateway data processing charges.

Step-by-Step Solution

1
Analyze the source and destination of the expensive traffic.
The source is EC2 instances in a private subnet, and the destination is Amazon S3 in the same AWS Region.
This establishes that the traffic is destined for an AWS service that supports Gateway VPC endpoints.
2
Evaluate the cost characteristics of alternative routing options.
Gateway VPC endpoints for S3 are free of charge, whereas NAT Gateways and Interface VPC endpoints incur hourly and data processing fees.
This identifies the most cost-effective method to bypass the NAT Gateway for S3 traffic.
3
Ensure routing is correctly updated to apply the optimization.
Associating the Gateway VPC endpoint with the private subnet's route table inserts a routing entry for the S3 prefix list.
This configuration is required to actually redirect the S3 traffic away from the NAT Gateway.

Key Concept

Gateway VPC Endpoints for S3 cost optimization
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Topics

Data Transfer Cost Optimization

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