AWS Certified Developer – Associate — Question 33

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 price update, the old price will continue to be served from ElastiCache, leading to discrepancies in the product listing. Option B is incorrect since write-through caching would not retain outdated prices. Options C and D are irrelevant to the cache issue, focusing instead on read or write capacity, which does not address the immediate problem of stale data being displayed.