URL remapped to .local address

[Stephen Jonke]

What would cause a URL to map to a .local address when entered into the 
web browser? For example, the URL http://mydomain.com:1234/~jukebox 
(without an ending slash) turns into 
http://mylocalmachine.local/~jukebox/ which fails because I'm trying 
this while not on my local network. The machine "mylocalmachine" is 
behind an airport base station which has port mapping of port 1234 to 
port 80 on mylocalmachine. What's weird is that if I add an ending 
slash to the URL, then it works:  http://mydomain.com:1234/~jukebox/  
If I leave out the ending slash, it maps to the .local address.

When typing the same URL (http://mydomain.com:1234/~jukebox) into IE on 
Windows, it just fails to load, rather than actually changing on screen 
to the .local address. I'm presuming it really is changing to a .local 
address and IE for windows is just not showing that, but I'm not sure. 
Again if I provide the address with a following slash it works fine.

Note that entering the numeric IP address instead of mydomain.com still 
has the same result.

Am I running into a bug with the airport base stations port mapping, or 
did I set something up some time in the past that is doing this?

Steve