AWS Certified Developer – Associate — Question 340

A developer is migrating an on-premises web application to AWS. The web application allows users to log in and modify their user profiles. The web application consists of a web server and a relational database. The developer has created an Amazon Machine Image (AMI) that will be used to launch Amazon EC2 instances to provide the web server. The developer also has created a database in Amazon RDS.

As part of the migration, the developer wants to create an Amazon EC2 Auto Scaling group to launch the web server instances behind an Application Load Balancer. The launch configuration for the Auto Scaling group will specify the AMI for the web server.

Which additional step should the developer take to give the web application the ability to automatically scale?

Answer options

• A. Select an EC2 instance type that is large enough to handle increased demand.
• B. Create an Amazon ElastiCache cluster. Configure the web application to store session state in the cluster.
• C. Install the database on one of the EC2 instances. Recreate the AMI from that EC2 instance.
• D. Create an RDS read replica. Configure the web application to use the read replica for all read operations.

Correct answer: D

Explanation

Creating an RDS read replica (Option D) allows the database tier to scale horizontally by offloading read traffic from the primary database, preventing it from becoming a bottleneck as the web tier auto-scales. Option A relies on vertical scaling instead of automatic horizontal scaling, while Option C removes the benefits of a managed Amazon RDS database by hosting it on EC2. Option B helps with session handling but does not address database scaling issues.