topic nslookup failure - no servers could be reached in Operating System - Linux

nslookup failure - no servers could be reached

MikeL_4 — Mon, 09 Feb 2009 17:49:34 GMT

I have a new server that I cannot resolve server names through DNS... and when I try a nslookup it fails with:

[root@odccdds01 ~]# nslookup mailhost
;; connection timed out; no servers could be reached

and even if DNS isn't working why it doesn't look in /etc/hosts, as I put an entry in there also...

I have iptables off on the server:
[root@odccdds01 ~]# service iptables status
Firewall is stopped.

/etc/nssswitch.conf has following for hosts:
#hosts: db files ldap nis dns
hosts: files dns

/etc/resolv.conf contains:
search convergys.com
nameserver 155.90.250.207
nameserver 155.90.248.206

I'm not sure where to look at, or what next to try and resolve the issue.... any assistance would be appreciated...

Re: nslookup failure - no servers could be reached

Ivan Ferreira — Mon, 09 Feb 2009 18:10:52 GMT

The nslookup or hosts command on Linux won't search for a host in the /etc/hosts file even when specified in nsswitch.conf.

Use the ping commando to probe name resolution in that case or configure a working DNS server.

Re: nslookup failure - no servers could be reached

Andrew Cowan — Tue, 10 Feb 2009 09:11:36 GMT

Mike can you simply ping these name servers? Remember that your IP parameters must be set so that there is a valid route to them.

Re: nslookup failure - no servers could be reached

Steven E. Protter — Tue, 10 Feb 2009 20:32:38 GMT

Shalom,

The dns servers in /etc/resolv.conf are not providing answers.

Check that they can be pinged, and are providing answers. Check with their admins if needed.

SEP

Re: nslookup failure - no servers could be reached

B. Hulst — Wed, 11 Mar 2009 18:49:39 GMT

And you could also trace the ethernet interface with tcpdump on what packets go where and there contents...

# tcpdump