Your application is using ElastiCache to handle session state and cache for frequently accessed data. However, during peak times, users are complaining that your website is running very slowly. You checked the CloudWatch metrics for your application servers, and databases and cannot find any single issue. Moreover, you notice that your Redis Cluster is showing 40% CPU utilization. You also see that the other metrics are just at the normal ranges, and you get convinced that this issue is with CPU utilization. In this case, which is the best way to go with this issue?

Answer options:

A.Use both the CPU Utilization and EngineCPUUtilization metrics together to get a detailed understanding of CPU Utilization for your Redis clusters.
B.Increase the Connection Overhead parameter value.
C.Scale your application server by adding more EC2 instances.
D.Scale your cluster up by using a larger node type.

Correct Answer: A
EBS volume metrics
Elasticache usually gets two metrics to measure the CPU utilization. That is the EngineCPUUtilization and the CPU utilization. The CPU Utilization does not give complete visibility. In that, it gives us insights into the CPU utilization for instance, whereas the EngineCPUUtilization provides additional visibility to the CPU utilization of the Redis process level.
Option C and D are incorrect since we have to scale based on certain metrics to ensure that there are no underutilized resources hence saving costs. So, we have to establish a good metric and scale based on the metric, not to scale based on guesswork.
Option B is incorrect. It`s just a distractor.
https://aws.amazon.com/elasticache/redis/faqs/