Robert G. Brown rgb at
Sat Aug 2 14:42:14 EDT 2003

On Sat, 2 Aug 2003, Sanjoy Bandyopadhyay wrote:

> Hi,
> I have a cluster running Rh 7.3 with NIS server. The cluster was running
> fine. But suddenly after rebooting now the clients are having problems in
> recognizing the NIS domain server name. while booting the clients it says:
> Binding to the NIS domain: [OK]
> Listening for an NIS domail server............[FAILED]
> ypwhich on clients says 'Can't communicate with ypbind'
> ypbind, ypserv are running fine on the server.

Hmmm, so many possible causes.

If you say "suddenly after rebooting" and if it applies to all the
clients, I'd check the following:

  a) The network connection of the server.  All things being equal, I'd
have to say this is a prime candidate.  Don't forget to check the
wire(s) itself -- many is the perplexing networking or service problem
that turned out to be caused by somebody kicking a wire so that the plug
was no longer properly seated.  Check network connectivity in other ways
to -- is the switch port suddenly bad, do I need to power cycle the
switch (switches sometimes "wedge" and need a cycle to rebuild their
tables), and so forth.  On some switches it is possible to block
broadcasts -- NIS requires them, so be sure that this didn't get done by

  b) When you've eliminated hardware as a possible cause (and have
validated perfect network connectivity) then you can look for software
problems.  A "sudden" problem like this is odd -- perhaps you
accidentally updated with a broken RPM?  Perhaps somebody trashed a
table?  Did somebody update iptables or ipchains or change their rules
so port access is blocked that way?

See if checking out these systems solves it.  If not, in your next post
include more detail on your network and so forth.  Usually this kind of
thing is solved by doggedly testing one system at a time until the
culprit emerges, starting with the most likely.  Don't forget, you have
tools like tcpdump that will let you snoop the network packets one at a
time if necessary to be sure that they are indeed arriving at the server
from the clients.  I recall that you can turn on ypserv with -d for
debug to get a much more verbose operational mode to help debug as well.



> I will appreciate if anyone can help..
> Thanks.
> Sanjoy
> --------------------------------------------------------------------
> Dr. Sanjoy Bandyopadhyay         E-mail: sanjoy at
> Assistant Professor                                                
> Molecular Modeling Laboratory    Phone: 91-3222-283344  (Office)
> Department of Chemistry                 91-3222-283345  (Home)
> Indian Institute of Technology          91-3222-279938 (Home) 
> Kharagpur 721 302                Fax  : 91-3222-255303
> West Bengal, India.                     91-3222-282252
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Robert G. Brown	             
Duke University Dept. of Physics, Box 90305
Durham, N.C. 27708-0305
Phone: 1-919-660-2567  Fax: 919-660-2525     email:rgb at

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