Your web-based application uses a large RDS data store to write and read user profile information. The latest marketing campaign has increased traffic to the application by an order of magnitude. Users are reporting long delays when logging in after having signed up. Which solutions are valid approaches to addressing this lag? (Choose two.)
A. Employ ElastiCache to cache users’ credentials after their initial visit to reduce trips to the database from the web application.
B. Increase the number of EC2 instances allocated to your Auto Scaling group to spread out traffic on the web application tier.
C. Set up a Multi-AZ configuration for your RDS and round-robin requests between the two RDS instances to spread out traffic.
D. Set up a read replica configuration for your RDS and round-robin requests between all the replicas to spread out traffic.
Answer:A
Your web-based application uses a large RDS data store to write and read user profile information. The latest marketing campaign has increased traffic to the application by an order of magnitude. Users are reporting long delays when logging in after having signed up. Which solutions are valid approaches to addressing this lag? (Choose two.)
A. Employ ElastiCache to cache users’ credentials after their initial visit to reduce trips to the database from the web application. B. Increase the number of EC2 instances allocated to your Auto Scaling group to spread out traffic on the web application tier. C. Set up a Multi-AZ configuration for your RDS and round-robin requests between the two RDS instances to spread out traffic. D. Set up a read replica configuration for your RDS and round-robin requests between all the replicas to spread out traffic.
Explanation: Option “Set up a Multi-AZ configuration for your RDS and round-robin requests between the two RDS instances to spread out traffic” is invalid because Multi-AZ is a disaster recovery solution; the primary database is the only instance that can respond to traffic in normal operation (unless read replicas are also set up). Option “Employ ElastiCache to cache users’ credentials after their initial visit to reduce trips to the database from the web application” is valid; caching user data would reduce round trips to the database and should reduce lag for users. Option “Set up a read replica configuration for your RDS and round-robin requests between all the replicas to spread out traffic” also makes sense, as having additional databases from which to read should decrease network latency to a single RDS instance. Option “Increase the number of EC2 instances allocated to your Auto Scaling group to spread out traffic on the web application tier” is not helpful as the problem appears to be in retrieving credentials, not in the web tier itself.