AWS Certified Developer – Associate (DVA-C02) — Question 223

A developer has built a market application that stores pricing data in Amazon DynamoDB with Amazon ElastiCache in front. The prices of items in the market change frequently. Sellers have begun complaining that, after they update the price of an item, the price does not actually change in the product listing.

What could be causing this issue?

Answer options

• A. The cache is not being invalidated when the price of the item is changed.
• B. The price of the item is being retrieved using a write-through ElastiCache cluster.
• C. The DynamoDB table was provisioned with insufficient read capacity.
• D. The DynamoDB table was provisioned with insufficient write capacity.

Correct answer: A

Explanation

The correct answer is A because if the cache is not invalidated after an item's price is updated, it will continue to serve the old price stored in the cache. Option B is incorrect as a write-through cache should update the cache correctly. Options C and D pertain to capacity issues on the DynamoDB table, which would not directly cause the cache to serve outdated prices.