AWS Certified DevOps Engineer – Professional — Question 26

A company recently launched an application that is more popular than expected. The company wants to ensure the application can scale to meet increasing demands and provide reliability using multiple Availability Zones (AZs). The application runs on a fleet of Amazon EC2 instances behind an Application Load
Balancer (ALB). A DevOps engineer has created an Auto Scaling group across multiple AZs for the application. Instances launched in the newly added AZs are not receiving any traffic for the application.
What is likely causing this issue?

Answer options

• A. Auto Scaling groups can create new instances in a single AZ only.
• B. The EC2 instances have not been manually associated to the ALB.
• C. The ALB should be replaced with a Network Load Balancer (NLB).
• D. The new AZ has not been added to the ALB.

Correct answer: D

Explanation

The correct answer is D because the newly added Availability Zone must be included in the Application Load Balancer's configuration to ensure that traffic is routed to instances in that AZ. Option A is incorrect since Auto Scaling groups can span multiple AZs, and option B is wrong because there is no mention of the instances needing manual association if the ALB is properly configured. Option C is irrelevant as the ALB is suitable for this scenario.