Question 340
An architect is validating an enterprise AWS migration plan, the decisive constraint is: An application requires strict financial balance reads and a proposed eventually consistent cache may show obsolete values. What is the most appropriate design under these constraints?
Explanation
Correct Answer
Bypass the cache for critical reads and use an appropriate strongly consistent data path. Strong consistency requirements can outweigh the performance benefit of stale cached data.
Incorrect Answers
For the separate situation A global media site retrieves the same files from origin for most requests despite a CloudFront distribution, Inspect cache-key headers, cookies and TTL policies to improve cacheability could be useful. Excessive cache-key variation fragments edge cache hit rates.
Review TTL, key distribution and read-through cache population solves the related scenario An ElastiCache deployment shows a high miss rate and database traffic did not fall; cache effectiveness depends on repeated keys and suitable expiration rules.
Although Add explicit invalidation or short TTL for critical mutable inventory fields can be valid when A product API returns stale inventory levels after cache entries are updated elsewhere, it targets a different technical condition. Cache-coherence controls bound staleness when the underlying source changes.