Yesterday I was writing a stand-alone .html web-page. Every time I viewed it, the file was run in the local host. Thus a port number was assigned by my OS (Windows 8).
I simply right-click over the file in VS2012 and select: 'View in Browser (Google Chrome)'
Doing so in Visual Studio fires up the ASP.net Dev server. It's not Windows that assigns it (nor configures it)
Update: Unsure if this will be a solution for you:
If you click the "wrench" icon of the dev server in your tray, you will see this:
The executable is in:
c:\Program Files (x86)\Common Files\microsoft shared\DevServer\11.0>
(for VS 2012)
If you run it via cmd line, this will pop (instructions):
So if I ran it via cmd line:
webdev.webserver40 /port:8080 /path:"C:\Users\[my user name]\Desktop" /vpath: "/"
http://localhost:8080/htmlpage1.html
(this file is in my desktop) in any browser...stop
the instance running...Not elegant in any way, so.....