AWS Certified SysOps Administrator – Associate (legacy) — Question 521

An ecommerce site is using Amazon ElastiCache with Memcached to store session state for a web application and to cache frequently used data. For the last month, users have been complaining about performance. The metric data for the Amazon EC2 instances and the Amazon RDS instance appear normal, but the eviction count metrics are high.
What should be done to address this issue and improve performance?

Answer options

• A. Scale the cluster by adding additional nodes
• B. Scale the cluster by adding read replicas
• C. Scale the cluster by increasing CPU capacity
• D. Scale the web layer by adding additional EC2 instances

Correct answer: B

Explanation

High eviction counts indicate that the cache is running out of memory, causing older keys to be dropped to make room for new ones, which degrades performance. Adding read replicas helps offload read traffic and scale read capacity to handle high-demand caching needs. Other options, such as scaling the web layer or increasing CPU, do not resolve the memory limitations causing the high eviction rate.