On 11/18/2010 5:16 AM, Matus UHLAR - fantomas wrote:
On 17.11.10 11:10, Moore, Mark A. wrote:
Subject: Nslookup not working for external domain
oh, nslookup is not working? Sure it is working, your problem is not in
nslookup.
We are running into a issue where one of our slave servers isn't resolving
non-local domain names.
the term "slave" only applies for domains server is fetchying from its
master. There's no "slave" for non-local domains.
For the two domains hosted on this server, we can resolve any entry.
However, if we try to do an nslookup to cnn, google, yahoo, etc. it fails.
We have turned off iptables and verified internet connectivity. Below is
the error we get. What other areas should we be looking at to
troubleshoot?
Thx in advance for any help given.
nslookup www.cnn.com
;; Got SERVFAIL reply from 192.243.160.18, trying next server
This server apparently does not provide recursion for you.
The OP already found the problem - - apparently the hints file wasn't
being loaded properly.
However, for future reference in troubleshooting DNS problems through
interpretation of nslookup results, for the versions of nslookup I'm
familiar with, trying to do a lookup that requires recursion, from a
resolver that doesn't provide it, results in either
a) a goofy-looking referral response, if no searchlisting is being
performed, or
b) nslookup going off and doing searchlisted queries, and returning the
results of the *last* query it does (which is likely to be an NXDOMAIN
response, thus causing nslookup to mis-report the result of the overall
lookup as NXDOMAIN)
In neither case would it return SERVFAIL. That usually points to some
other root cause. My guess would have been that the resolver had no
connectivity to the Internet and had marked all of the root nameservers
as "lame". Mis-loading of the hints file apparently has the same
symptoms, although to be honest I don't think I've seen that before.
- Kevin
P.S. Nslookup sucks.
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