boot problems

how do change the boot-device? it currently is this:
boot-device disk disk net
it tells me the system is coming up, but than it starts checking ufs filesystems and begins looking for NIS domainname and can’t find a carrier because its not hooked up to the NIS server. this is the first i have ever run into this (i am not too experienced) and i don’t know how to fix it… can anyone help me?i need to change the disk net, but i don’t know how.