Simple TCP based connectivity testing of a web site e.g. via Pandora FMS or Telnet is possible but Apache and IIS work differently.
With Apache you can (using telnet as the example) connect to the host on port 80 then type in GET / HTTP/1.0 and hit return twice and you will get a HTTP/1.1 200 OK message
You won’t on IIS but you will get a HTTP/1.1 400 Bad Request message. To get the 200 message from IIS you need to send,
HEAD / HTTP/1.1^M
where the ^M is the return or enter key.