Key points

• Caching requires explicit population, expiration, invalidation, miss, and failure behavior.
• A cache can reduce database reads but does not fix writer pressure or a mismatched data model.
• Topology, engine, persistence expectations, memory sizing, and network placement determine resilience and cost.

Best-known use cases

• Cache frequently read database results.
• Store compatible sessions, counters, or ephemeral low-latency data.

What candidates often confuse it with

• ElastiCache returns cached data; RDS Proxy pools database connections without caching results.
• A read replica serves database queries broadly; a cache wins for repeatable hot reads tolerant of cache semantics.

Key takeaway

Choose ElastiCache when reusable data can trade controlled staleness and complexity for much lower latency and origin load.

Related services

• Amazon RDS
• Amazon Aurora
• Amazon DynamoDB

Relevant exam tasks

• D2.1
• D3.3
• D4.3

Learn more

• Amazon ElastiCache