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Difficulty: Very hardHigh-Performing and Elastic Compute Solutions

A financial technology enterprise runs a distributed transaction clearing simulation on AWS that requires high-throughput and sub-millisecond node-to-node latency for parallel processing. The workload runs on a fleet of compute-optimized EC2 instances. An internal Application Load Balancer (ALB) routes traffic to these instances. The clearing application listens and processes requests on TCP port 8443, but the target group's health check is left configured to the default HTTP port (80).

During testing, the solutions architect observes two major issues:
1. The load balancer marks all target instances as unhealthy, causing connection failures.
2. The processing nodes experience high network latency during synchronization phases, which limits the platform's overall throughput.

Which combination of actions will resolve both of these issues?

  1. A
    Configure the target group to perform health checks on port 8443. Launch the EC2 instances in a partition placement group spread across multiple Availability Zones.
  2. B
    Keep the target group health check port configured to port 80. Launch the EC2 instances in a spread placement group within a single Availability Zone.
  3. Configure the target group to perform health checks on port 8443. Launch the EC2 instances in a cluster placement group within a single Availability Zone.Answer
  4. D
    Configure the target group to perform health checks on port 8443. Launch the EC2 instances in a cluster placement group distributed across multiple Availability Zones.

Answer

Configure the target group to perform health checks on port 8443, and launch the EC2 instances in a cluster placement group within a single Availability Zone.
The correct configuration involves modifying the target group's health check port to 8443, which aligns with the port where the backend transaction clearing daemon is listening. This allows the load balancer to successfully complete health checks and mark the instances as healthy. Additionally, placing the EC2 instances in a cluster placement group within a single Availability Zone ensures the instances are placed close together on physical hardware, providing the low latency and high network throughput required for tightly coupled processing.

Step-by-Step Solution

1
Identify the port mismatch in the target group health check configuration.
Determine that the ALB is sending health check requests to port 80, whereas the clearing application runs on port 8443.
To ensure the ALB can correctly monitor the health of the application, the health check port must match the port where the backend service is listening.
2
Update the target group health check port settings.
Configure the target group health checks to query port 8443 instead of the default port.
This allows the load balancer to receive successful health check responses and mark the target instances as healthy.
3
Analyze the node-to-node latency requirements.
Identify that the application requires sub-millisecond node-to-node latency for parallel transaction clearing.
Tightly coupled distributed applications need a specialized placement group strategy to minimize physical distance and network hops between hosts.
4
Select and configure the appropriate EC2 placement group.
Deploy the EC2 instances within a cluster placement group in a single Availability Zone.
A cluster placement group packages instances close together inside the same Availability Zone, enabling low-latency, high-throughput network performance.

Key Concept

Optimizing compute performance and resolving load balancer target health check issues by aligning application ports and using EC2 cluster placement groups.
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Topics

High-Performing and Elastic Compute Solutions

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