AWS Certified Solutions Architect – Professional — Question 985

A financial services company loaded millions of historical stock trades into an Amazon DynamoDB table. The table uses on-demand capacity mode. Once each day at midnight, a few million new records are loaded into the table. Application read activity against the table happens in bursts throughout the day, and a limited set of keys are repeatedly looked up. The company needs to reduce costs associated with DynamoDB.
Which strategy should a solutions architect recommend to meet this requirement?

Answer options

• A. Deploy an Amazon ElastiCache cluster in front of the DynamoDB table.
• B. Deploy DynamoDB Accelerator (DAX). Configure DynamoDB auto scaling. Purchase Savings Plans in Cost Explorer.
• C. Use provisioned capacity mode. Purchase Savings Plans in Cost Explorer.
• D. Deploy DynamoDB Accelerator (DAX). Use provisioned capacity mode. Configure DynamoDB auto scaling.

Correct answer: D

Explanation

DynamoDB Accelerator (DAX) is ideal for caching repeated read requests of a limited key set, which offloads read traffic and reduces read capacity costs. Transitioning to provisioned capacity mode with auto scaling is more cost-effective than on-demand capacity for predictable daily write bursts and daytime read patterns. Amazon ElastiCache requires complex application-side changes compared to DAX, and Savings Plans do not apply to DynamoDB table capacity.