Q43 — AWS DVA-C02 Ch.3

Question 43 of 100 | ← Chapter 3

A developer built a retail application that stores pricing data in Amazon DynamoDB, with Amazon ElastiCache in front. Retail product prices change frequently. Customers began complaining that after they update a product price, the price displayed in the product listing does not change immediately.

• A. The cache is not invalidated when product prices change. ✓
• B. Using a write-through ElastiCache cluster to retrieve product prices.
• C. The DynamoDB table is configured with insufficient read capacity.
• D. The DynamoDB table is configured with insufficient write capacity.

Correct Answer: A. The cache is not invalidated when product prices change.

Explanation

The key issue is that updated product prices are not reflected in the product listing. With Amazon ElastiCache acting as a caching layer in front of DynamoDB, stale cached data will be served if the cache is not properly invalidated or updated upon backend changes. Option A correctly identifies that failure to invalidate the cache upon price updates causes users to see outdated values. Option B mischaracterizes write-through caching — it relates to write operations, not stale reads. Options C and D refer to capacity limits, which would cause throttling or latency, not stale data. Therefore, the correct answer is A.