An Auto-Scaling group spans 3 AZs and currently has 4 running EC2 instances.
When Auto Scaling needs to terminate an EC2 instance by default, AutoScaling will:
Choose 2 answers
Allow at least five minutes for Windows/Linux shutdown scripts to complete, before terminating
Terminate the instance with the least active network connections. If multiple instances meet this
criterion, one will be randomly selected.
Send an SNS notification, if configured to do so.
Terminate an instance in the AZ which currently has 2 running EC2 instances.
Randomly select one of the 3 AZs, and then terminate an instance in that AZ.
Auto Scaling determines whether there are instances in multiple Availability Zones. If so, it
selects the Availability Zone with the most instances and at least one instance that is not
protected from scale in.