IIS 7.0 and above impotent error messages
200 - OK. The client request has succeeded.
400 - Bad request. The request could not be understood by the server due to malformed syntax. The client should not repeat the request without modifications.
401 - Access denied.
403 - Forbidden.
404 - Not found.
500 - Internal server error.
501 - Header values specify a configuration that is not implemented.
502 - Web server received an invalid response while acting as a gateway or proxy.
503 - Service unavailable.