Explanation

Correct Answer: D - Deploy an S3 VPC gateway endpoint into the VPC and attach an endpoint policy that allows access to the S3 buckets.

Why Option D is Correct:

1. S3 VPC Gateway Endpoints: These are specifically designed to allow private connectivity between your VPC and Amazon S3 without requiring an internet gateway, NAT device, VPN connection, or AWS Direct Connect.

2. Cost Reduction: When using S3 VPC endpoints:

   • Data transfer between your VPC and S3 in the same AWS Region is free (no data transfer charges)
   • Traffic stays within the AWS network and doesn't traverse the public internet
   • Eliminates NAT gateway data processing charges

3. Security Benefits:

   • Traffic remains within the AWS network
   • Can use endpoint policies to restrict access to specific S3 buckets
   • No exposure to the public internet

Why Other Options Are Incorrect:

A. Deploy Amazon API Gateway into a public subnet and adjust the route table to route S3 calls through it.

• API Gateway is for creating RESTful APIs, not for optimizing S3 access
• This would add complexity and potentially increase costs
• Doesn't address the data transfer fee issue

B. Deploy a NAT gateway into a public subnet and attach an endpoint policy that allows access to the S3 buckets.

• NAT gateways incur data processing charges ($0.045 per GB)
• Traffic still goes through the public internet
• Doesn't reduce data transfer costs

C. Deploy the application into a public subnet and allow it to route through an internet gateway to access the S3 buckets.

• This is the current problematic setup
• Uses public internet, incurring data transfer fees
• Least secure option

Key AWS Concepts:

• VPC Endpoints: Provide private connectivity to AWS services
• S3 Gateway Endpoints: Specifically for S3, free data transfer within same region
• Endpoint Policies: IAM-like policies to control access through the endpoint

Best Practice:**

When applications in a VPC need frequent access to S3 in the same region, always use S3 VPC gateway endpoints to eliminate data transfer costs and improve security.