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what dns server is doing the resolving

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Timothy P. Jackson
Valued Contributor

what dns server is doing the resolving

Hi everyone,

I am trying to figure out a DNS issue on my HP server, of course it could be with the DNS servers them selves.

system - rp3440
OS - HP-UX 11i version 1

When I do an nslookup for ttksg.com it comes back with no response from server.

so from nslookup I do a....

server 74.127.128.30

Then try it again and it works.

How do I know what server my DNS is trying to use by default.

My resolv.conf is....

domain barrelofunsnacks.com
74.127.128.30
172.17.8.72
172.17.8.73

I just entered the top dns server just to try it and see if the other two were just not working.

My nsswitch.conf is.....

hosts: files [NOTFOUND=continue UNAVAIL=continue] dns [NOTFOUND=return UNAVAIL=continue TRYAGAIN=return]

any help would be greatly appreciated!!

Tim
5 REPLIES
cnb
Honored Contributor

Re: what dns server is doing the resolving

When you first invoke nslookup without any quailifiers, it will tell you the default server. However you should read the manpages for resolv.conf.

from the manpage:
EXAMPLES
A typical resolv.conf file resembles the following:

domain div.inc.com
nameserver 15.19.8.119
nameserver 15.19.8.197

WARNINGS
In order to reduce situations that may cause connections to unintended
destinations, the administrator should carefully select which domains
are put in the search list in the resolv.conf file. HP recommends
that the possible domains for the search list be limited to those
domains administered within your trusted organization. For more
information on the security implications of search lists please see
RFC 1535.

Rgds,
Timothy P. Jackson
Valued Contributor

Re: what dns server is doing the resolving

When I do an nslookup it tells me it is using /etc/hosts.... Maybe that is my problem. I will reboot the system and see if that helps.
cnb
Honored Contributor

Re: what dns server is doing the resolving

change your nsswitch.conf to see if this will help:

hosts: files dns nis
Bill Hassell
Honored Contributor
Solution

Re: what dns server is doing the resolving

> nslookup ...

Not the best choice to look at resolver issues. Use nsquery instead:

nsquery hosts ttksg.com

The resolver looks at resolv.conf top down so the first query is the first attempt. However, you can force nslookup to bypass the hosts and resolv.conf files and look at just one DNS server:

nslookup ttksg.com 74.127.128.30
or
nslookup ttksg.com 172.17.8.73


Bill Hassell, sysadmin
Timothy P. Jackson
Valued Contributor

Re: what dns server is doing the resolving

using nsquery I was able to figure out that there was an issue with the resolv.conf file.