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Your application is using an ELB in front of an Auto Scaling group of web/application servers deployed across
two AZs and a Multi-AZ RDS Instance for data persistence.
The database CPU is often above 80% usage and 90% of I/O operations on the database are reads. To improve
performance you recently added a single-node Memcached ElastiCache Cluster to cache frequent DB query
results. In the next weeks the overall workload is expected to grow by 30%.
Do you need to change anything in the architecture to maintain the high availability or the application with the
anticipated additional load’* Why?

A.
Yes. you should deploy two Memcached ElastiCache Clusters in different AZs because the ROS Instance will
not Be able to handle the load It me cache node fails.

B.
No. if the cache node fails the automated ElastiCache node recovery feature will prevent any availability
impact.

C.
Yes you should deploy the Memcached ElastiCache Cluster with two nodes in the same AZ as the RDS DB
master instance to handle the load if one cache node fails.

D.
No if the cache node fails you can always get the same data from the DB without having any availability
impact.

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