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Subject : Re: LUG: DNS settings

From : Will Brockelsby <will@ncstate.[redacted]>

Date : Wed, 18 Mar 2009 09:20:13 -0400

Parent

Daniel,
You can set the domain search list to any domain that you want
although it probably does make sense for you to set it to ie.ncsu.edu if
that is the department that your system is in ( search functionality is
there for convenience ). You can actually add up to six domains to be
searched. Check out the resolv.conf man page for additional information.

The stub resolver that is part of the C library uses the DNS server
information configured in /etc/resolv.conf. Changes to /etc/resolv.conf
are immediate, however, if your system is using nscd ( name service
cache daemon ) you will likely want to restart nscd -- see the nscd man
page for additional information.

Having said the above, we have noticed a few cases where atypical
applications use a special resolver library that caches the contents of
/etc/resolv.conf when started. In these cases the application would
need to be restarted to obtain the new DNS server IP addresses.

You can always use tcpdump to see what DNS servers your machine is querying:

/usr/sbin/tcpdump -v port 53

If you use the above command and see that your machine is still querying
the incorrect DNS servers after updating /etc/resolv.conf and restarting
nscd ( if applicable ), you can look for atypical applications or take
the easy way out and reboot the system.

Thanks --Will

--
Will Brockelsby
Network Systems Engineer
Communication Technologies
Office of Information Technology
North Carolina State University




Daniel Underwood wrote:
> Thanks for the assistance.
>
> You wrote as an example:
>
> search comtech.ncsu.edu
> nameserver 152.1.1.206
> nameserver 152.1.1.248
>
> But, for this computer, which is in the ie.ncsu.edu domain, the first
> line should be the following, correct?
>
> search ie.ncsu.edu
>
> Also, how are the changes enacted? Are they automatically enacted?
> Enacted upon reboot?
>
> Thanks,
> Daniel
>
>
> ------------------------------------------------------------------------
>
> Subject:
> Re: LUG: DNS settings
> From:
> Will Brockelsby <will@ncstate.[redacted]>
> Date:
> Wed, 18 Mar 2009 08:49:05 -0400
> To:
> lug@lists.ncsu.[redacted]
>
> To:
> lug@lists.ncsu.[redacted]
>
>
> Daniel,
> You can edit /etc/resolv.conf and specify the correct DNS
> servers. As an example:
>
> ----------------------------------------------------------------
> $ cat /etc/resolv.conf
>
> search comtech.ncsu.edu
> nameserver 152.1.1.206
> nameserver 152.1.1.248
> ----------------------------------------------------------------
>
> Let me know if you have any further questions. Thanks --Will
>

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