DOP-C02 Question 284
Select 3Your company operates a web application hosted on an Auto Scaling group of EC2 instances behind an Application Load Balancer (ALB). You also use Amazon Route 53 for DNS routing, configured with a weighted routing policy to balance traffic between two regions. Recently, users have reported intermittent downtime when accessing the application. After investigation, you discover that some unhealthy instances in one region are still receiving traffic. What steps should you take to ensure traffic is only routed to healthy instances?
- A
Configure health checks for the ALB target group to automatically remove unhealthy instances.
- B
Set up Route 53 health checks for the ALB endpoints in each region and integrate them with the weighted routing policy.
- C
Enable Cross-Zone Load Balancing on the ALB to ensure traffic is balanced across all instances in both regions.
- D
Increase the health check interval for the ALB target group to reduce the frequency of health checks.
- E
Ensure the Auto Scaling group is configured to replace unhealthy instances automatically.
Show answer and explanation
Correct answers: A, B, E
Explanation
To prevent downtime and ensure traffic is routed only to healthy instances, you need to configure health checks at multiple levels. ALB health checks ensure unhealthy instances within a region are not used, while Route 53 health checks integrated with routing policies ensure traffic is not sent to an entire region if its ALB or instances are unhealthy. Additionally, Auto Scaling ensures that unhealthy instances are replaced, maintaining the desired capacity of the application.
- A. Correct.
Configuring health checks for the ALB target group ensures that the ALB only routes traffic to healthy instances. This is a fundamental step in maintaining application availability.
- B. Correct.
Route 53 health checks can be used to monitor the health of the ALB endpoints in each region. By integrating these health checks with the routing policy, Route 53 can stop routing traffic to regions where the ALB or its target instances are unhealthy.
- C. Incorrect.
Enabling Cross-Zone Load Balancing balances traffic across all instances in multiple AZs within a region but does not address the issue of routing traffic to unhealthy instances in another region.
- D. Incorrect.
Increasing the health check interval would delay the detection of unhealthy instances and exacerbate the problem, leading to extended downtime for users.
- E. Correct.
Auto Scaling groups can replace unhealthy instances automatically, which ensures that healthy instances are available to handle traffic.