If you work on any type of web farm or cluster, they'll come a time when you have to figure out what web server you are actually hitting. Sure you could enable tracing, but this comes with consequences (like an application restart). Something I've gotten into the habit of on every site I work on is including the server name and last date/time refreshed in comments at the bottom of the page.
<!-- Connected To: <%= HttpContext.Current.Server.MachineName.ToString().ToUpper() %> -->
<!-- Last Refreshed: <%= DateTime.Now.ToShortDateString() + " " + DateTime.Now.ToLongTimeString() %> -->
Time after time again, I thank myself for doing this..