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Zorluk: KolayAuto Scaling and Elastic Load Balancing (ELB)

A company hosts a simple web application on Amazon EC2 instances managed by an Auto Scaling group (ASG) behind an Application Load Balancer (ALB). The ASG health check type is configured to use EC2 status checks. When the web application process crashes on an instance, the ALB marks that instance as unhealthy and stops routing traffic to it. However, the ASG does not terminate or replace the instance because the underlying EC2 instance status checks remain healthy. Which configuration change should a solutions architect implement to ensure that instances with failed web application processes are automatically replaced?

  1. Configure the Auto Scaling group health check type to use ELB health checks.Cevap
  2. B
    Change the health check port in the Application Load Balancer target group to query the default HTTP port 80 instead of the custom application port.
  3. C
    Modify the inbound Network Access Control List (NACL) rules of the public subnets to allow stateful TCP traffic from the Application Load Balancer.
  4. D
    Create an Amazon Route 53 latency routing policy to direct user traffic to a backup Auto Scaling group in another AWS Region.

Cevap

Configure the Auto Scaling group health check type to use ELB health checks.
By default, an Auto Scaling group (ASG) only monitors EC2 status checks. If the application process crashes but the OS/hypervisor remains healthy, the ASG will not replace the instance. Configuring the ASG to use ELB health checks allows it to query the Application Load Balancer's target group status, triggering the automatic replacement of instances that fail application-level health checks.

Adım Adım Çözüm

1
Analyze the current health check configuration of the Auto Scaling group (ASG) and Application Load Balancer (ALB).
The ASG is configured to use EC2 health checks, which only monitor the hardware and hypervisor status, whereas the ALB is performing application-level health checks on the targets.
This explains why the ASG does not replace instances when the web application process crashes but the EC2 instance remains running.
2
Identify the mechanism required to link the ALB's health check results to the ASG's lifecycle management.
The health check type of the ASG must be updated from EC2 to ELB.
This configuration allows the ASG to receive health status updates from the ALB target group and take corrective action (termination and replacement) when the application health check fails.

Anahtar Kavram

Auto Scaling Group Health Check Configuration
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Konular

Auto Scaling and Elastic Load Balancing (ELB)

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