DOP-C02 Question 286
Select 3Your company has deployed a web application using an Auto Scaling group behind an Application Load Balancer (ALB). Users have reported intermittent connectivity issues when accessing the application. Upon investigation, you notice that some unhealthy instances are still receiving traffic. To resolve this issue, you want to ensure that only healthy instances receive traffic. Additionally, you want to implement DNS-based health checks to improve failover between regions. Which combination of actions should you take?
- A
Configure health checks on the ALB target group to evaluate the health of the instances.
- B
Set up Route 53 DNS health checks to monitor the endpoint of the ALB.
- C
Enable cross-zone load balancing on the ALB to distribute traffic evenly across all instances.
- D
Ensure the Auto Scaling group has a health check grace period set to 0 seconds.
- E
Use Route 53 weighted routing policy to route traffic only to healthy endpoints.
Show answer and explanation
Correct answers: A, B, E
Explanation
To ensure that only healthy instances receive traffic, you need to configure health checks on the ALB target group. Additionally, to achieve regional failover and route traffic based on health, you can use Route 53 DNS health checks and weighted routing policies. These configurations together improve the reliability and availability of your application.
- A. Correct.
This is correct. ALB target group health checks are essential to ensure that the load balancer routes traffic only to healthy instances. Without this, unhealthy instances could continue to receive traffic.
- B. Correct.
This is correct. Route 53 DNS health checks can be used to monitor the endpoint of the ALB and redirect traffic to a healthy region if the ALB or its instances are unhealthy.
- C. Incorrect.
This is incorrect. Cross-zone load balancing helps distribute traffic evenly across all instances in all zones but does not address the issue of unhealthy instances receiving traffic.
- D. Incorrect.
This is incorrect. Setting the Auto Scaling group health check grace period to 0 seconds could cause premature termination of instances during startup. A reasonable grace period should be configured instead.
- E. Correct.
This is correct. Weighted routing in Route 53 can be used in conjunction with health checks to ensure traffic is routed only to healthy endpoints based on their health status.