Um . . .  Just keep making DHCP requests?

--
LTP

Open a socket on a well-known port on each of the hosts in your LAN. If this
is a small LAN, most likely it will be type C network, with up to 254 hosts.
So, start with the host 1, and loop over:
192.168.1.1
192.168.1.2
...
192.168.1.254

(e.g. if your network IP starts with 192.168.1), and see if the socket
throws an exception. To speed things up, you can open 254 sockets at the
same time in asynchronous threads.

Alex Molochnikov
Gestalt Corporation

You know the range of IPs typically used.  See
http://mindprod.com/jglass/ip.html

You probe each machine.  If you can't find a way to talk to it, it is
as if it did not exist.