AWS Certified Solutions Architect – Associate (SAA-C03) — Question 577

A company runs a web application on Amazon EC2 instances in an Auto Scaling group behind an Application Load Balancer that has sticky sessions enabled. The web server currently hosts the user session state. The company wants to ensure high availability and avoid user session state loss in the event of a web server outage.

Which solution will meet these requirements?

Answer options

• A. Use an Amazon ElastiCache for Memcached instance to store the session data. Update the application to use ElastiCache for Memcached to store the session state.
• B. Use Amazon ElastiCache for Redis to store the session state. Update the application to use ElastiCache for Redis to store the session state.
• C. Use an AWS Storage Gateway cached volume to store session data. Update the application to use AWS Storage Gateway cached volume to store the session state.
• D. Use Amazon RDS to store the session state. Update the application to use Amazon RDS to store the session state.

Correct answer: B

Explanation

Amazon ElastiCache for Redis is an in-memory key-value store that supports replication and Multi-AZ deployments, providing the high availability and data persistence needed to prevent session loss during EC2 instance failures. While Memcached can store sessions, it does not natively support replication for high availability. Amazon RDS and AWS Storage Gateway are not optimized for the sub-millisecond latency requirements of active session state management.