Explanation: Auto Scaling can determine the health status of an instance using custom health checks. If you have custom health checks, you can send the information from your health checks to Auto Scaling so that Auto Scaling can use this information. For example, if you determine that an instance is not functioning as expected, you can set the health status of the instance to Unhealthy. The next time that Auto Scaling performs a health check on the instance, it will determine that the instance is unhealthy and then launch a replacement instance.
Reference:
http://docs.aws.amazon.com/AutoScaling/latest/DeveloperGuide/health…