Ping is no help to you. Ping is a networking debugging tool. To check whether a service is running, you will have to actually use the service. Request the page (using your favourite module). And go one step further than what the other replies are saying. Don't just look for a 200 status response. Also look at what you are actually getting is what you think you should be getting. A misconfigured Apache server, or one running on a machine having DNS problems, might serve a default page instead of the (virtual) hosts pages.

Abigail