AWS Certified Solutions Architect – Professional — Question 727

A company is hosting a critical application on a single Amazon EC2 instance. The application uses an Amazon ElastiCache for Redis single-node cluster for an in-memory data store. The application uses an Amazon RDS for MariaDB DB instance for a relational database. For the application to function, each piece of the infrastructure must be healthy and must be in an active state.

A solutions architect needs to improve the application's architecture so that the infrastructure can automatically recover from failure with the least possible downtime.

Which combination of steps will meet these requirements? (Choose three.)

Answer options

• A. Use an Elastic Load Balancer to distribute traffic across multiple EC2 instances. Ensure that the EC2 instances are part of an Auto Scaling group that has a minimum capacity of two instances.
• B. Use an Elastic Load Balancer to distribute traffic across multiple EC2 instances. Ensure that the EC2 instances are configured in unlimited mode.
• C. Modify the DB instance to create a read replica in the same Availability Zone. Promote the read replica to be the primary DB instance in failure scenarios.
• D. Modify the DB instance to create a Multi-AZ deployment that extends across two Availability Zones.
• E. Create a replication group for the ElastiCache for Redis cluster. Configure the cluster to use an Auto Scaling group that has a minimum capacity of two instances.

Correct answer: A, D

Explanation

To achieve high availability and automatic recovery for the application tier, deploying an Elastic Load Balancer alongside an Auto Scaling group with at least two EC2 instances ensures that traffic is distributed and failed instances are replaced automatically (Option A). For the database tier, migrating the Amazon RDS for MariaDB instance to a Multi-AZ deployment provides automatic failover to a standby instance in a different Availability Zone with minimal downtime (Option D). Other options, such as creating same-AZ read replicas or attempting to configure ElastiCache with Auto Scaling groups, do not support proper automated failover and recovery.