>If it's the built in ASP.NET development server then it's almost certainly still using localhost (i.e. 127.0.0.1) even if it doesn't display that way. But it's not clear whether what you are seeing allows you to discern the port that's being used...........
>So where are you seeing this value ?
>If it's in the bottom toolbar then double clicking the icon should bring up a window showing the root URL and port.

This is returned from the .NET Framework Process object if I remember correctly. I am not there at the office right now so I can't double check that.