An application is hosted in an AWS Auto Scaling group. The ASG has a scheduled action that adds more instances at 8:00 AM every day. The cooldown timer of the ASG is set as 45 minutes and it takes about 30 minutes for a new instance to finish its init scripts and serve traffic. One day, the ASG scaled up at 7:45 AM because a high CPU alarm was triggered in AWS CloudWatch. What will happen for the scheduled scaling activity on that day?

Answer options:

A.The scheduled scaling activity will start at 8:45 AM as the cooldown timer is reset when the scheduled activity starts and the scheduled scaling can only start until the cooldown timer expires.
B.The scheduled scaling activity will start at 8:30 AM as it needs to wait for the cooldown timer to expire.
C.The scheduled scaling activity starts immediately as the scheduled action does not wait for the cooldown period to expire.
D.The scheduled scaling will not start this time as it is overridden by the active cooldown timer. The scheduled scaling will continue to work the next day.

Correct Answer – C
Options A and B are incorrect because there are some scaling actions that do not need to wait for the cooldown period to expire such as a scheduled or a manual scaling action.
Option C is CORRECT because the cooldown timer does not influence the scheduled activity. Even if the cooldown timer is running, the scheduled action takes high priority and executes immediately.
Option D is incorrect because the active cooldown timer does not override the scheduled activity. At 8:00 AM, the scheduled scaling takes action immediately.
Reference:
https://docs.aws.amazon.com/autoscaling/ec2/userguide/schedule_time.html,
https://docs.aws.amazon.com/autoscaling/ec2/userguide/Cooldown.html.