The default scripts fire off ypbind and yppasswdd before
launching ypserv. This, obviously, does not work on the NIS
server. A simple workaround (I don't know if it's correct or
not, but it does fix the problems) is to renumber the start
and kill scripts to switch ypbind and ypserv. Probably,
yppasswdd should start after ypbind as well, but I haven't
yet had problems with them reordered.
this has been fixed in a later release of ypserv. (1.3.5-3, IIRC)