A company is using Amazon RDS as the backend database for its application. After a recent marketing campaign, a surge of read requests to the database increased the latency of data retrieval from…

Question

Options

• AAmazon CloudFront
• BAmazon ElastiCache for Memcached
• CAmazon ElastiCache for Redis in cluster mode
• DAmazon DynamoDB Accelerator (DAX)

• A
  2% (1)
• B
  9% (4)
• C
  84% (38)
• D
  4% (2)

Explanation

Amazon ElastiCache for Redis in cluster mode satisfies both requirements: it provides in-memory caching to offload read traffic from RDS, supports encryption at rest and in transit, and delivers high availability through automatic failover with Multi-AZ replication across cluster nodes.

• A (CloudFront) is a CDN designed to cache static web content at edge locations - it's not a database caching layer and doesn't sit in front of RDS.
• B (ElastiCache for Memcached) supports caching and encryption, but lacks built-in replication, so it cannot provide high availability - a node failure means data loss.
• D (DAX) is a caching service purpose-built for DynamoDB, not RDS - it won't integrate with a relational database backend.

Memory tip: Think "Redis = Replication = Reliable." When an exam question requires both encryption and high availability for a caching layer in front of RDS, Redis in cluster mode is almost always the answer because Memcached is the "simpler but limited" sibling that lacks HA and persistence.

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