1st. question. How is your setup? Can you draw it or describe it?
2nd. question. How many nics does this server have?
3rd. question. You seem to have several subnets, is it all on the same nic and if so, is it VLANed...?
Also... There's a file under /etc/sysconfig and it's called dhcpd and it should look something like this:
Or whatever the nic is that should hand out IP's.
Hope I can help you but to do so I need a little more info...