>         Stupid NIS question:  why should the primary server use NIS 
> for its name service accesses, as the O'Reilly book states?
> 

The users in YP will have accounts and passwords on the master server,
unless you build the password map from some other file than 
'/etc/master.passwd'.  If the server itself also uses YP, you can
use the "netgroups" mechanism to prevent those users from log-ing
in to the YP master.

David S.