problem with setting gateway or to find

I have a mate that as linux using Red Hat and the server crashed and the gateway is reading 0.255.255.255, I have read in sa book that this should not be a good idea but could not find anything on how to change it.

Since the crash of the server we can telnet in to the network but if we try to log in at the username prompt does not work. Think it is to do with the gateway being 0.255.255.255 so on.

if anyone got any ideas please let me know