Explanation:
Each time a change is made to one of your supported resources, AWS config will check its compliance against any Config Rules that you have in place. If there is a violation against these rules then AWS Config will send a message to the Configuration Stream via SNS and the resource will be marked as `noncompliant’.
It’s important to note that this does not mean the resource will be taken out of service or it will stop working.
It will continue to operate exactly as it is with its new configuration. AWS Config simply alerts you that there is a violation and it’s up to you to take the appropriate action.
Reference: http://docs.aws.amazon.com/config/latest/developerguide/evaluate-config_view-compliance.html