AWS Certified Database – Specialty — Question 269

A news portal is looking for a data store to store 120 GB of metadata about its posts and comments. The posts and comments are not frequently looked up or updated. However, occasional lookups are expected to be served with single-digit millisecond latency on average.

What is the MOST cost-effective solution?

Answer options

• A. Use Amazon DynamoDB with on-demand capacity mode. Purchase reserved capacity.
• B. Use Amazon ElastiCache for Redis for data storage. Turn off cluster mode.
• C. Use Amazon S3 Standard-Infrequent Access (S3 Standard-IA) for data storage and use Amazon Athena to query the data.
• D. Use Amazon DynamoDB with on-demand capacity mode. Switch the table class to DynamoDB Standard-Infrequent Access (DynamoDB Standard-IA).

Correct answer: D

Explanation

DynamoDB Standard-IA is the most cost-effective choice because it reduces storage costs for infrequently accessed data while still delivering single-digit millisecond latency. On-demand capacity mode is perfect for occasional lookups as you only pay for actual requests, whereas ElastiCache is too expensive for inactive data and Athena cannot meet the low-latency requirement. Additionally, purchasing reserved capacity is not supported for DynamoDB on-demand mode, making option A invalid.