Thanks ,I tried the single user mode and it still wouldnt boot up all the way. It keeps timing out when trying to communicate with NIS.
The way we have it set up here is we assigne ipaddress to the Mac. addresses of our machines using MIP then we have to manually set (or in my case change) the I.P. locally on the machine.
Ok... but it shouldn't be trying to communicate to NIS in single user mode (IIRC). Anyway, if you have a CD handy, boot up from the CD, mount root, then remove or rename /etc/defaultdomain and reboot.
EDIT:
Now that I read your original post again, I think there has to be something else here. the ifconfig command doesn't write to files, so after a reboot, whatever you set with ifconfig would've been lost.
Thanks for all your help....I got into the machine via single user mode and had to edit /etc/hosts and rename a dir. in /var/yp/binding/ and then create a file 'ypservers' within that directory. after that I was all good