If everything is fine (as it should be), you should be able to verify your installation with a few simple commands. Assuming, for example, your passwd file is being supplied by NIS, the command
% ypcat passwd
should give you the contents of your NIS passwd file. The command
% ypmatch userid passwd
(where userid is the login name of an arbitrary user) should give you the user's entry in the NIS passwd file. The "ypcat" and "ypmatch" programs should be included with your distribution of traditional NIS or NYS.