Examkin

Question

Difficulty: EasyAuto Scaling and Elastic Load Balancing (ELB)

A company runs a web application on Amazon EC2 instances behind an Application Load Balancer (ALB). The EC2 instances are managed by an Auto Scaling group. The web application is configured to listen on custom port 8080. However, the ALB is currently marking all instances in the target group as unhealthy, preventing users from accessing the application. A solutions architect verifies that the application is running normally on the instances. Which action should the solutions architect take to resolve this issue?

  1. A
    Configure the target group to forward traffic and run health checks on port 80.
  2. Update the ALB target group's health check configuration to use port 8080.Answer
  3. C
    Create a stateful Network Access Control List (NACL) rule allowing traffic on port 80 to enable the return traffic from the health checks.
  4. D
    Change the Amazon Route 53 routing policy to Latency routing to distribute traffic directly to the instances.

Answer

Update the ALB target group's health check configuration to use port 8080.
Updating the health check port to 8080 allows the Application Load Balancer to perform health checks directly against the port where the web application is listening, correctly identifying the instances as healthy.

Step-by-Step Solution

1
Identify the port on which the web application is listening on the EC2 instances.
The application listens on custom port 8080.
This is the actual port where health checks must be directed to confirm application availability.
2
Compare this with the load balancer health check configuration.
The default health check configuration queries port 80, which is not receiving any response from the instances.
This mismatch explains why the ALB is reporting the instances as unhealthy.
3
Modify the target group's health check settings.
The health checks are updated to query port 8080.
This ensures the ALB validates the application's actual listening port, restoring the healthy status of the instances.

Key Concept

Aligning Elastic Load Balancing health checks with custom application ports
Estimated Time:1m 0s
Rate this question

Topics

Auto Scaling and Elastic Load Balancing (ELB)

More questions from this topic