Desde a versão 5.8, a Monit tem a status
opção :
STATUS option can be used to explicitly test the HTTP status code returned by the HTTP server. If not used, the http protocol test will fail if the status code returned is greater than or equal to 400. You can override this behaviour by using the status qualifier.
For example to test that a page does not exist (404 should be returned in this case):
if failed port 80 protocol http request "/non/existent.php" status = 404 then alert