Correct answer - "The ASG will terminate the EC2 Instance" : To maintain the same number of
instances, Amazon EC2 Auto Scaling performs a periodic health check on running instances within
an Auto Scaling group. When it finds that an instance is unhealthy, it terminates that instance
and launches a new one. Amazon EC2 Auto Scaling creates a new scaling activity for terminating
the unhealthy instance and then terminates it. Later, another scaling activity launches a new
instance to replace the terminated instance.
Incorrect:
"The ASG will detach the EC2 instance from the group, and leave it running" - The goal of the
auto scaling group is to get rid of the bad instance and replace it
"The ASG will keep the instance running and re-start the application" - The ASG does not have
control of your application
"The ASG will format the root EBS drive on the EC2 instance and run the User Data again" - This
will not happen, the ASG can make no assumption about the format of your EBS drive and User Data
only runs once at instance first boot.