SUMMARY: DNS and applications

From: Terry Franklin (
Date: Thu Feb 10 2000 - 13:50:32 CST

Thanks to responders, especially to Pete Durst who responded:

"The problem is related to how the system is used for each of the tools. The "nslookup" tool goes directly to the DNS server and works there. The other tools work from the client perspective, and will consult locally cached information. There is a daemon called "Name Server Cache Daemon" that is running, and it will have cached the older information on each client. Each of the tools will consult the cache, and get the wrong answer. Your solution caused the nscd to flush, thus getting the right answer. As an alternative, stop/restart the client nscd. The information will time out, according to you DNS settings, if you want to wait."

and to Matthew Fansher who pointed me to the nscd man pages.

Thanks, all!


original post:

  Hi all,
  I've got something confusing me ... we made an IP address change of a host in our DNS tables, and sent a SIGHUP to named on our primary and two secondary DNS servers internally. Within nslookup, all three DNS servers resolved the name correctly to the new address. However applications such as ping and telnet still were resolving to the old address. Switching the order of the 3 DNS servers in the client's resolv.conf fixed the problem.
  What I don't understand is why, if nslookup resolves correctly using any of our 3 DNS servers, ping or telnet etc still resolved incorrectly? (nsswitch.conf is set to "dns files" and there is no corresponding entry in the host file)
  Thanks for any input and I will summarize

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