SUMMARY: dns failover problem

From: Patrick Novak <>
Date: Thu May 30 2002 - 14:29:44 EDT
Many thanks for your prompt and useful replies

Dan Astoorian, John Riddoch and Brett Lymn all provided the correct
information, and that is:

nslookup is flawed. it is a troubleshooting tool and doesn't use
the same resolver mechanism that is used when a normal
dns lookup is being performed. It uses only one server at a time-
the first one listed in resolv.conf.

as I was testing a failover configuration for our dns, it became
apparent that I should use something that mimics the dns lookup
process more closely.

"getent hosts" was the appropriate command
and did produce the desired results. when named was running
on box and getent hosts was entered,
the appropriate ip address was returned. I killed the named pid
on and getent hosts came back
with the proper ip address.

Pat Novak

Original email:

>I have 2 dns's, joined by a hub, set up as master and slave.  both have
>entered as default routers, and both have each other listed in the
>resolv.conf file as
> second nameserver entry, and themselves as the first.  The slave finds and
>from the master as expected.

>the box at ip has resolv.conf entries of:


>and  box at has:

>if,  on dns A,  i say "nslookup"      it resolves.
>if,  on dns A,  i say "nslookup   dns.B.ip"  it resolves.
>and vice versa

>however, if i test a failover on box A by killing named-pid, then do:
>"nslookup"  i get no response and truss shows the
>process sleeping. i get the same result going the other way.
>has anyone else seen this,  or have i missed something obvious.

>Pat Novak
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Received on Thu May 30 14:36:43 2002

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