Are there any monitoring services, like Pingdom, that do external 3rd party auditing of current DNS endpoints for a domain and offer alerting whenever a change

Are there any monitoring services, like Pingdom, that do external 3rd party auditing of current DNS endpoints for a domain and offer alerting whenever a change is made? That service (being external from the registrar or DNS provider) seems sorely needed by everyone in our industry because this method of attack is starting to become the standard.