AWS Certified DevOps Engineer – Professional (DOP-C02) — Question 254
A company has an application that runs on Amazon EC2 instances behind an Application Load Balancer (ALB). The EC2 instances are in multiple Availability Zones. The application was misconfigured in a single Availability Zone, which caused a partial outage of the application.
A DevOps engineer made changes to ensure that the unhealthy EC2 instances in one Availability Zone do not affect the healthy EC2 instances in the other Availability Zones. The DevOps engineer needs to test the application's failover and shift where the ALB sends traffic. During failover, the ALB must avoid sending traffic to the Availability Zone where the failure has occurred.
Which solution will meet these requirements?
Answer options
- A. Turn off cross-zone load balancing on the ALB. Use Amazon Route 53 Application Recovery Controller to start a zonal shift away from the Availability Zone.
- B. Turn off cross-zone load balancing on the ALB’s target group. Use Amazon Route 53 Application Recovery Controller to start a zonal shift away from the Availability Zone.
- C. Create an Amazon Route 53 Application Recovery Controller resource set that uses the DNS hostname of the ALB. Start a zonal shift for the resource set away from the Availability Zone.
- D. Create an Amazon Route 53 Application Recovery Controller resource set that uses the ARN of the ALB’s target group. Create a readiness check that uses the ElbV2TargetGroupsCanServeTraffic rule.
Correct answer: A
Explanation
The correct answer is A because turning off cross-zone load balancing on the ALB ensures that traffic is not routed to the unhealthy Availability Zone, while using Amazon Route 53 Application Recovery Controller allows for a zonal shift away from the failure. Options B and D incorrectly target the ALB’s target group instead of the ALB itself, which does not meet the requirement of avoiding traffic to the failed zone. Option C incorrectly relies on the DNS hostname rather than the ALB for effective failover management.