Your company has a set of EC2 Instances hosted on the AWS Cloud. As an architect, you have been told to ensure that if the status of any of the instances is related to failure, then the instances should restart automatically. How can you achieve this in the most efficient way possible?

Answer options:

A.Create CloudWatch alarms that stop and start the instance based off of status check alarms.
B.Write a script that queries the EC2 API for each instance status check.
C.Write a script that periodically shuts down and starts instances based on certain stats.
D.Implement a third-party monitoring tool.

Answer – A
Using Amazon CloudWatch alarm actions, you can create alarms that automatically stop, terminate, reboot, or recover your EC2 instances. You can use the stop or terminate actions to help you save money when you no longer need an instance to be running. You can use the reboot and recover actions to automatically reboot those instances or recover them onto new hardware if a system impairment occurs.
All other options are possible but would be an extra maintenance overhead.
For more information on using alarm actions, please refer to the below link-
http://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/UsingAlarmActions.html