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Difficulty: EasyAuto Scaling and Elastic Load Balancing (ELB)

A company is deploying a new web application on Amazon EC2 instances managed by an Auto Scaling group (ASG) behind an Application Load Balancer (ALB). The solutions architect needs to ensure that the ALB only routes traffic to instances that are running the web service successfully, and that the ASG automatically terminates and replaces any instance where the web service has failed. Which two configurations should the solutions architect implement to meet these requirements? (Select two.)

  1. Set the Auto Scaling group health check type to ELB.Answer
  2. Configure the Application Load Balancer target group health check to monitor the specific port and path where the web application is running.Answer
  3. C
    Configure the Application Load Balancer target group health check to use the default port 80 while the web application is configured to listen on a custom port.
  4. D
    Update the subnet Network Access Control Lists (Network ACLs) to be stateful to allow return health check traffic.
  5. E
    Create a Route 53 Latency routing policy to automatically detect failed EC2 instances and remove them from the target group.

Answer

To meet the requirements, the solutions architect must set the Auto Scaling group health check type to ELB and configure the Application Load Balancer target group health check to monitor the specific port and path where the web application is running.
Configuring the Auto Scaling group to use ELB health checks ensures that the group will replace instances if they fail the application-level load balancer health checks. Configuring the Application Load Balancer target group health check to monitor the specific port and path where the web application is running ensures that the load balancer correctly identifies whether the application itself is healthy, rather than just the underlying EC2 instance.

Step-by-Step Solution

1
Determine how the Auto Scaling group monitors instance health.
By default, the Auto Scaling group only performs EC2 status checks (system and instance status checks), which do not detect if the web server process has crashed.
To ensure the Auto Scaling group replaces instances when the web application fails, the health check type must be updated to ELB.
2
Determine how the Application Load Balancer monitors application health.
The target group health check must be configured to query the specific port and path where the web application is active.
This ensures the load balancer accurately tracks application health and redirects traffic away from failed instances.

Key Concept

ELB and Auto Scaling Group Health Check Integration
Estimated Time:1m 0s
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Topics

Auto Scaling and Elastic Load Balancing (ELB)

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