AWS Certified Solutions Architect – Professional (SAP-C02) — Question 434

A company uses a mobile app on AWS to run online contests. The company selects a winner at random at the end of each contest. The contests run for variable lengths of time. The company does not need to retain any data from a contest after the contest is finished.

The company uses custom code that is hosted on Amazon EC2 instances to process the contest data and select a winner. The EC2 instances run behind an Application Load Balancer and store contest entries on Amazon RDS DB instances. The company must design a new architecture to reduce the cost of running the contests.

Which solution will meet these requirements MOST cost-effectively?

Answer options

• A. Migrate storage of the contest entries to Amazon DynamoDB. Create a DynamoDB Accelerator (DAX) cluster. Rewrite the code to run as Amazon Elastic Container Service (Amazon ECS) containers that use the Fargate launch type. At the end of the contest, delete the DynamoDB table.
• B. Migrate the storage of the contest entries to Amazon Redshift. Rewrite the code as AWS Lambda functions. At the end of the contest, delete the Redshift cluster.
• C. Add an Amazon ElastiCache for Redis cluster in front of the RDS DB instances to cache the contest entries. Rewrite the code to run as Amazon Elastic Container Service (Amazon ECS) containers that use the Fargate launch type. Set the ElastiCache TTL attribute on each entry to expire each entry at the end of the contest.
• D. Migrate the storage of the contest entries to Amazon DynamoDB. Rewrite the code as AWS Lambda functions. Set the DynamoDB TTL attribute on each entry to expire each entry at the end of the contest.

Correct answer: D

Explanation

AWS Lambda offers a serverless compute option that charges only for actual execution time, making it ideal and highly cost-effective for contests with variable durations. Using Amazon DynamoDB to store entries provides a low-cost, fully managed NoSQL database, and enabling DynamoDB TTL (Time to Live) automates the deletion of expired entries at no additional cost. The other options introduce unnecessary overhead and expenses, such as maintaining Amazon Redshift clusters, DAX clusters, or ECS Fargate tasks.