Question

A SysOps administrator manages an EC2 Auto Scaling group behind an Application Load Balancer for a web tier. The group uses a target tracking scaling policy set to keep average CPU utilization at 50%. During a marketing event, traffic spiked and the group scaled out correctly. After the event, traffic dropped sharply, but the administrator notices the group is removing instances very slowly, keeping many instances running for a long time at low CPU. The administrator wants faster scale-in while still avoiding thrashing during brief traffic dips. What is the MOST appropriate action?

Accepted Answer

Keep target tracking but tune the scale-in behavior by lowering the default instance warmup/cooldown period to a shorter value appropriate for the workload.

Answer

Reduce the target value of the CPU target tracking policy to 30% so instances are removed sooner.

Answer

Add a scheduled scaling action to set the desired capacity to the minimum after the event window ends.

Answer

Disable the scale-in cooldown entirely and lower the instance warmup so scale-in reacts immediately.