You have created a new Auto Scaling group for a new application which sets the minimum capacity as 1 and the maximum capacity as 20. The ASG is running well for two weeks. However, recently there were cases that some instances were not terminated successfully. You need to work out a way to notify the team via email whenever any instance fails to terminate. What is the simplest way to implement this?

Answer options:

A.Configure the Auto Scaling group to send a notification to an SNS topic whenever instances fail to terminate.
B.Configure the related Auto Scaling configuration to send a notification to an SNS topic whenever instances fail to terminate.
C.Create a CloudWatch Event. When an event of “Terminate Unsuccessful” happens, invoke a Lambda function to notify the team.
D.Create a CloudWatch alarm based on the metric of “Terminate Failed”. Send a notification to an SNS topic when the alarm state is “ALARM”.

Correct Answer – A
Auto Scaling group can be easily configured to send an SNS notification whenever it scales. The details can be found in https://docs.aws.amazon.com/autoscaling/ec2/userguide/ASGettingNotifications.html.
Option A is CORRECT: Because this is the simplest way and can be configured directly in the ASG console:
Option B is incorrect: Because the Auto Scaling configuration cannot be used to set up an SNS notification.
Option C is incorrect: Because an SNS notification should be used as a target instead of a Lambda function for a CloudWatch Event.
Option A is more straightforward than Option
C.Option D is incorrect: Because ASG does not provide a CloudWatch metric of “Terminate Failed”.