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Difficulty: HardAuto Scaling and Elastic Load Balancing (ELB)

A company hosts a specialized data processing service on Amazon EC2 instances. The instances are managed by an Auto Scaling group (ASG) behind an Application Load Balancer (ALB). The backend application runs on custom port 80808080. The target group is configured to route traffic to the instances on port 80808080, but the default health checks are failing, and the ALB marks all newly launched instances as unhealthy. Additionally, during scale-in events, active client connections—which can take up to 1010 minutes (600600 seconds) to complete—are being terminated abruptly before finishing their tasks.

Which two actions should a Solutions Architect take to resolve these issues? (Select two.)

  1. Set the deregistration delay timeout attribute of the ALB target group to 600600 seconds.Answer
  2. Modify the target group's health check configuration to explicitly use port 80808080.Answer
  3. C
    Add an outbound rule to the subnet's Network ACL (NACL) to statefully track and allow active connections on port 80808080 during instance termination.
  4. D
    Configure an Amazon Route 53 latency-based routing policy to direct client traffic away from instances that are terminating during scale-in.
  5. E
    Configure the target group's default port to 8080 and enable sticky sessions (session affinity) with a cookie duration of 600600 seconds.

Answer

Setting the target group deregistration delay to 600600 seconds and modifying the health check configuration to target port 80808080 explicitly.
The correct options are to increase the target group's deregistration delay to 600600 seconds and explicitly set the health check port to 80808080. Increasing the deregistration delay allows active transactions to complete gracefully during scale-in. Explicitly targeting port 80808080 in the health check ensures the load balancer accurately monitors the backend application.

Step-by-Step Solution

1
Analyze the connection termination issue.
Identified that the default deregistration delay (connection draining) is forcing active connections to drop before the 1010-minute (600600-second) window needed by the processing tasks.
By increasing the deregistration delay to 600600 seconds, the ALB allows in-flight requests to complete before terminating the EC2 instance.
2
Analyze the health check failure issue.
Identified that target group health checks are targeting the wrong port (e.g., port 8080) instead of the application's active listening port (80808080).
Setting the health check port explicitly to 80808080 ensures the ALB queries the port where the backend service is actually running.

Key Concept

ELB connection draining (deregistration delay) configuration and target group port mapping for health checks.
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Topics

Auto Scaling and Elastic Load Balancing (ELB)

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