Web Sharing on Lion

Web Sharing on Lion... I'm doing it now...

There's something that intrigues me though... instead of the website being my external IP as all of the old Snow Leopard Tutorials show, it has (my computer name).bigpond

Bigpond being my ISP provider... is this new or is this just something from bigpond?

So basically, if my computer's name was John (which it isn't) my website would be

http://john.bigpond

Wierd?

 

So I basically want to know what's happening... and whether or not my website will be available from those outside of my local network.

Have I just gotten myself a free domain? If so, is it registered, i.e. will no-one be able to make the same domain name?