I have never seen this take place anywhere before but now I have a need
for it and I'm looking desperately for a solution.

We have software that uses a certain port. We've set up the software
to allow access through our router by using its virtual server feature
(DLINK DI-707P) which takes the port and forwards the traffic coming to
that port of the outside IP address to an internal LAN IP.

The problem is this software can only run on one of our systems
internally at a time. We want to switch the use of this software
between computers as needed but the switch is configured to send all of
that data on that port to the internal IP that we set it to. We can go
in and change it each time but that would be a pain.

What I think I am looking for is a sort of Dynamic DNS for an internal
LAN. Something that is as simple as running a small application on
each machine and logging into the dynamic dns so that it will switch
that incoming traffic to the IP of the machine we just logged on to the
dynamic dns with.

Am I making any sense? Is this doable yet? Can anybody write an app
that will handle it? Can it actually be done using W2K Server with the
DHCP and DOMAIN SERVER installed on it?