The Receive String needs to be set to something the application will produce in the response to the Send String request. The question is whether or not string "example.com" or "test.com" is something that the pool produces consistently in the content served by either site's default page (as specified by the GET/\r\n Send String). If the default page does not return either of these character strings anywhere in the HTTP response (headers or body), then the monitor will fail. The Receive String does not apply to what the client sends (as presented to the virtual server), it applies to what the server responds with, as requested by the monitor's Send String.