Q13 — AWS DOP-C02 Ch.3

Question 13 of 100 | ← Chapter 3

A company recently launched an application that became more popular than expected. The company wants to ensure the application can scale to meet growing demand and achieve high availability across multiple Availability Zones (AZs). The application runs on a set of Amazon EC2 instances behind an Application Load Balancer (ALB). A DevOps engineer created an Auto Scaling group spanning multiple AZs for the application. However, EC2 instances launched in newly added AZs receive no traffic from the application. What could cause this issue?

• A. An Auto Scaling group can launch new instances only in a single AZ.
• B. EC2 instances have not been manually registered with 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. The new AZ has not been added to the ALB.

Explanation

D: The new AZ has not been added to the ALB. Explanation: If EC2 instances in a newly added Availability Zone (AZ) are not correctly registered with the Application Load Balancer (ALB), those instances will not receive traffic. This typically requires ensuring the ALB’s target groups include all relevant AZs and associated instances. Analysis of other options: A: Incorrect — Auto Scaling groups can launch instances across multiple AZs. B: Partially true — Instances usually auto-register with target groups if configured correctly; manual registration is not required unless misconfigured. C: Incorrect — ALB is appropriate for HTTP/HTTPS application-layer load balancing; NLB is unnecessary here.