SAP-C02 Question 349
Select 2Your company is running a multi-tier web application hosted on AWS. The application consists of an Amazon EC2 Auto Scaling group in a public subnet for the web tier, a private subnet with an Amazon RDS instance for the database tier, and an Amazon S3 bucket for static content. Recently, the monthly AWS bill shows a significant increase in data transfer costs. Which of the following changes could help reduce data transfer costs?
- A
Configure an Amazon CloudFront distribution for the static content stored in the S3 bucket.
- B
Move the Amazon RDS instance to a public subnet to reduce data transfer charges.
- C
Enable VPC endpoints for S3 to allow private communication between the EC2 instances and the S3 bucket.
- D
Use EC2 instances with Elastic IPs instead of public IPs in the Auto Scaling group.
- E
Deploy the application entirely in a single Availability Zone to avoid inter-AZ data transfer costs.
Show answer and explanation
Correct answers: A, C
Explanation
Data transfer costs in AWS can escalate due to traffic leaving the AWS environment or crossing boundaries (e.g., between Availability Zones or to the internet). Using CloudFront reduces internet-bound traffic charges by caching content closer to users. Enabling VPC endpoints ensures data stays within the AWS private network, eliminating charges for traffic leaving the VPC. These solutions are effective at optimizing costs without compromising security or availability.
- A. Correct.
Correct: Using Amazon CloudFront will cache your static content closer to end users, reducing the amount of outbound data transfer from your S3 bucket to the internet, which can significantly reduce costs.
- B. Incorrect.
Incorrect: Moving the RDS instance to a public subnet increases security risks and does not reduce data transfer costs. Data transfer within the same VPC is free, regardless of whether the subnet is public or private.
- C. Correct.
Correct: Enabling VPC endpoints for S3 ensures that data transfer between your EC2 instances and S3 occurs over the AWS private network, avoiding data transfer charges for traffic leaving the VPC.
- D. Incorrect.
Incorrect: Using Elastic IPs does not impact data transfer costs. It only ensures a static IP address, which is unrelated to reducing transfer charges.
- E. Incorrect.
Incorrect: While deploying in a single Availability Zone avoids inter-AZ transfer costs, this approach reduces the application’s availability and resilience, which is a poor trade-off for the small reduction in data transfer costs.