In /var/yp/Makefile are lines
# We do not put password entries with lower UIDs (the root and system
# entries) in the NIS password database, for security. MINUID is the
# lowest uid that will be included in the password maps. If you
# create shadow maps, the UserID for a shadow entry is taken from
# the passwd file. If no entry is found, this shadow entry is
# ignored.
# MINGID is the lowest gid that will be included in the group maps.
MINUID=500
MINGID=500

If you have users with user or group id below 500, you'll have to either
increase their user or group id's, or you can change the MINUID and/or
MINGID and set up NIS again.  But I admit that the hypothesis of too low
uid or gid doesn't seem consistent with what you said about ypcat working.
I would expect `ypcat passwd` to not show users whose uid or gid are
too low.

Steven Yellin

On Sat, 11 Feb 2006, Kuo Kan Liang wrote:

> Dear all,
>
> I have a cluster on which I set up NIS and NFS. For the first three user
> accounts I set up, there is no problem using them. But later I added a
> few new users, and they could not login to any of the NIS client. They
> complained that there are not these users. However, if I use ypcat,
> yptest, ypwhich, etc., on each client thest tests all pass. If I list
> the contents of the NFSed /home directory, I found that the system could
> not recognize the uid and gid of these new accounts. That is, it seems
> that NIS setup is fine, but somehow the system does not use those
> informations. I am totally exausted by this problem now. Can someone
> give me some clues? Thanks in advance!
>
> --
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Dr. Kuo Kan LIANG
> Laboratory of Digital Chemical Kinetics (DICK)
> Thematic Center for Mechanics and Engineering Sciences (TCMES)
> Research Center for Applied Sciences (RCAS)
> Academia Sinica (AS)
> 128, Section 2, Academia Road, Nankang
> Taipei 115, Taiwan
> FAX: +886-2-27826680
> Email: kkliang_at_ntu.edu.tw; kkliang_at_sinica.edu.tw
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>