AWS Certified SysOps Administrator – Associate (legacy) — Question 858

An application is running on Amazon EC2 instances behind an Application Load Balancer (ALB). The instances are configured in an Amazon EC2 Auto Scaling group. A SysOps Administrator must configure the application to scale based on the number of incoming requests.
Which solution accomplishes this with the LEAST amount of effort?

Answer options

• A. Use a simple scaling policy based on a custom metric that measures the average active requests of all EC2 instances
• B. Use a simple scaling policy based on the Auto Scaling group GroupDesiredCapacity metric
• C. Use a target tracking scaling policy based on the ALB's ActiveConnectionCount metric
• D. Use a target tracking scaling policy based on the ALB's RequestCountPerTarget metric

Correct answer: A

Explanation

Using a simple scaling policy with a custom metric that tracks average active requests across EC2 instances allows the Auto Scaling group to scale dynamically in direct response to the actual workload. Other metrics like GroupDesiredCapacity do not reflect real-time incoming traffic demands, and connection counts do not map precisely to request volumes. This custom metric approach ensures the application scales accurately based on the active load per instance.