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Zorluk: OrtaAuto Scaling and Elastic Load Balancing (ELB)

A company runs a high-traffic web application on a fleet of Amazon EC2 instances managed by an Auto Scaling group (ASG). The application is configured to listen on custom port 8080. The instances are registered with a target group behind an Application Load Balancer (ALB) that routes external traffic from port 443 to the target group. A solutions architect must configure health checks to ensure that the ASG accurately detects and replaces instances that fail at the application layer, while maintaining a secure and highly available setup.

Which configuration should the solutions architect implement?

  1. A
    Configure the target group to perform health checks on default port 80 to simplify load balancer configurations, while allowing the instances to process application requests on port 8080.
  2. B
    Modify the subnet Network ACL to allow inbound traffic on port 8080, and rely on the stateful nature of Network ACLs to automatically allow outbound ephemeral port return traffic to the Application Load Balancer.
  3. Configure the target group health check to query the application's status path on port 8080, and update the Auto Scaling group to use Elastic Load Balancing (ELB) health checks. Ensure the security groups allow traffic from the ALB to the instances on port 8080.Cevap
  4. D
    Configure Route 53 with Latency routing to distribute incoming requests across multiple AWS Regions, using the latency policy as the primary mechanism to fail over and reroute traffic away from unhealthy EC2 instances without configuring Route 53 health checks.

Cevap

Configure the target group health check to query the application's status path on port 8080, and update the Auto Scaling group to use Elastic Load Balancing (ELB) health checks. Ensure the security groups allow traffic from the ALB to the instances on port 8080.
Configuring the target group health check to query the status path on port 8080 ensures that the ALB tests the actual application port. Setting the Auto Scaling group to use ELB health checks allows the ASG to terminate and replace instances that fail the ALB health checks, maintaining resilience at the application layer. Standard security group rules must also allow port 8080 traffic between the ALB and the instances.

Adım Adım Çözüm

1
Configure the target group health check to match the application's listening port.
The target group is configured to query the custom application port (8080) instead of the default HTTP port (80).
The Application Load Balancer needs to verify the health of the application on the specific port where the application service runs, preventing false-negative health statuses.
2
Integrate the Auto Scaling Group health checks with the Elastic Load Balancer.
The Auto Scaling Group is updated to use ELB health checks in addition to standard EC2 instance status checks.
By default, the ASG only monitors EC2 status (e.g., hardware/hypervisor failures). Adding ELB health checks ensures the ASG replaces instances that fail at the application layer.
3
Establish secure network routing rules for health checks and traffic.
Security groups are configured to allow inbound traffic from the ALB on port 8080, and Network ACLs are configured to permit stateless ephemeral return traffic.
Security groups must allow communication between the load balancer and the targets, and stateless Network ACLs must explicitly allow return traffic to avoid blocking connections.

Anahtar Kavram

Aligning target group health checks with custom application ports, enabling ELB health checks in the Auto Scaling group, and satisfying stateful security group and stateless Network ACL rules.
Tahmini Süre:2m 0s
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Konular

Auto Scaling and Elastic Load Balancing (ELB)

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