The deployment team has recently deployed a new application on the Amazon EC2 instance launched in an Auto Scaling group. The Operations Team is monitoring the Amazon EC2 instance using Amazon CloudWatch. Team Lead wants to be notified only when multiple metrics are all in ALARM state. For cost optimization, Auto scaling groups should scale in based upon CPU utilization.
What alarm can be created to meet this requirement?

Answer options:

A.Create a metric alarm to initiate a scale-in action for Auto Scaling Group based upon CPU utilization & to notify SNS topics.
B.Create a metric alarm to initiate a scale-in action for Auto Scaling Group based upon CPU utilization while creating a composite alarm to notify SNS topics.
C.Create a composite alarm to initiate a scale-in action for Auto Scaling Group based upon CPU utilization & to notify SNS topics.
D.Create a composite alarm, initiate a scale-in action for Auto Scaling Group based upon CPU utilization & create a metric alarm to notify SNS topics.

Correct Answer: B
A metric alarm watches a single CloudWatch metric which can be used to initiate actions on AWS resources or notify SNS topics.A composite alarm considers the state of multiple metric alarms or composite alarm states which it is part of before going into ALARM mode. A composite alarm helps to reduce the number of notifications. But it cannot initiate actions based upon the ALARM state.
Option A is incorrect as a composite alarm would be preferred to be used over a metric alarm to notify. With Metric alarms, clients will get notifications for every alarm in an ALARM state.
Options C & D are incorrect as composite alarms can only notify SNS topics, it does not take action to initiate a scale-in action for Auto Scaling Group based upon CPU utilization.
For more information on alarms with Amazon CloudWatch, refer to the following URL,
https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/Create_Composite_Alarm.html