Question

A CloudOps engineer manages an EC2 Auto Scaling group spanning three Availability Zones behind an Application Load Balancer. After a recent AZ impairment, one AZ was temporarily removed and instances were relaunched in the two remaining AZs. Now that all three AZs are healthy again, the engineer notices the group has 8 instances in AZ-a, 8 in AZ-b, and only 2 in AZ-c, creating an uneven distribution. What is the MOST appropriate way to ensure the group automatically restores balanced capacity across all three AZs going forward?

Accepted Answer

Rely on the Auto Scaling group's built-in Availability Zone rebalancing, which launches instances in under-provisioned AZs and terminates instances in over-provisioned AZs to even out distribution.

Answer

Manually terminate three instances each in AZ-a and AZ-b so the group launches replacements evenly across all AZs.

Answer

Attach a target-tracking scaling policy on CPU utilization so scaling activity redistributes instances across the AZs.

Answer

Create a scheduled action that sets desired capacity to zero nightly and back to 18 each morning to force even redistribution.