Setting up different Document Root on one web server?

Maybe I shouldn't have changed the document root to set a demo web-site up on DynDNS. Now I'm screwed because I can't run any of our other sites (internally). This external thing is only for a couple of weeks (probably). My quick solution was to change DocumentRoot to the base of what I want the external users to see. I thought I'd finally get down to creating A Virtual Host on this box and that would fix my troubles.
Hmmm.
So now I can see the same site that faces externally-- on two different ports locally-- :80 or :8080

That's not what I wanted!

I want :80 and :8080 to have two different Document Root s on the same server. Do I want multiple/two IP's (as in eth0 alias) or two ports (done but not showing different sites) or two web servers. (I can do the extra web server bit, but I figure there really is a better way, and it probably falls under the category Networking. Am I right there?)

Basic requirement is that the external facing site on port 80 looks like it is the only site!

The index file has some info and a link to click to log in.
That must stay the same.

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I don't want to set up another web server just for a week or two. So I started investigating the all too oft ignored aliases, and I'm not sure how to split up two DocumentRoots on one server.

Maybe this is an apache2 question. I really think it's Network (cause if it was Apache I'd understand right? ha! ha! Not always.)

??

Sure it's simple once you know :-)

If I can understand well what you want to achieve, then you have to follow this example.

Regards

NameVirtualHost by golly, I think that will do it.
Thanks.
I'll let you know how it goes :-)