Q22 — AWS DOP-C02 Ch.2
Question 22 of 100 | ← Chapter 2
A company recently migrated a legacy application from on-premises to AWS. The application runs on Amazon EC2 instances behind an Application Load Balancer, which is itself behind Amazon API Gateway. The company wants to minimize disruption to users during deployment of new application versions. The company also wants to ensure rapid rollback if issues arise. Which solution satisfies these requirements with minimal changes to the application?
- A. Introduce the change as a separate, parallel environment alongside the existing environment. Configure API Gateway to use canary deployment to route a small percentage of user traffic to the new environment. ✓
- B. Introduce the change as a separate, parallel environment alongside the existing environment. Update the application’s DNS alias record to point to the new environment.
- C. Introduce the change as a separate target group behind the existing Application Load Balancer. Configure API Gateway to gradually route user traffic to the new target group.
- D. Introduce the change as a separate target group behind the existing Application Load Balancer. Configure API Gateway to route all traffic to the Application Load Balancer, which then forwards traffic to the new target group.
Correct Answer: A. Introduce the change as a separate, parallel environment alongside the existing environment. Configure API Gateway to use canary deployment to route a small percentage of user traffic to the new environment.
Explanation
Option A provides independence (new environment runs parallel to production), progressive validation (small traffic slice enables testing stability), and fast rollback (canary can be halted immediately). Option B suffers from DNS propagation delays and caching, causing inconsistent user experiences and difficult rollback. Option C introduces complexity in target group and routing rule configuration, increasing risk of misconfiguration. Option D adds unnecessary latency and management overhead, and risks impacting all traffic if the new target group fails.