You have developed a web application to collect monthly expense reports. As the nature of the application and looking at the usage statistics, it is mostly used around the last week of the month and the first week of the month. To increase the application performance, you added a caching layer in front of the application servers. So the reports are cached and served immediately. You started off with Elasticache Redis with a "cache.t2.small" node type. The application has been running fine. When looking at the performance activity into the CloudWatch, hardly 50% of the requests are served by the cache, and the cache cannot cope with additional content requirements. You want to improve the application with minimal changes and resources. Please select a valid option.

Answer options:

A.Modify the ElastiCache instance from t2 small to t2 medium, as t2 medium is more suitable for the given requirement.
B.Create a new ElastiCache instance with t2 micro, and terminate the t2 small instance.
C.Migrate the application to Elastic Beanstalk to use auto-scaling and set the desired and min capacity to 1, use the RDS and Cache layer of Beanstalk to save the cost.
D.Run the web application from S3 and serve with CloudFront.

Correct Answer: A
Option A is CORRECT because we can modify the cache node type from "cache.t2.small" to "cache.t2.medium" in the console. We must increase the size of the Redis instance for the server to serve more requests from the cache.
Option B is INCORRECT because creating a new Elasticache instance with a "cache.t2.micro" node type is not needed here.
Option C is INCORRECT because migrating to Beanstalk will simply not save the cost. Also, Beanstalk has an RDS layer but no caching layer.
Option D is INCORRECT because S3 and CloudFront will incur additional costs for such a minimal use case.
There are two things here.
Elastic Cache Instance -> this supports the underlying Elasticache engine. This is similar to our ec2 instance like "t2.micro" , "t2.mall" etc. This instance type can be modified either through the AWS console or through the CLI.
Redis -> This is the engine that runs the elasticache cluster. This engine can only be "upgraded" and cannot be "downgraded".
Please refer to page 99 of the below link-
https://docs.aws.amazon.com/AmazonElastiCache/latest/red-ug/redis-ug.pdf