Index
Subject
: Re: LUG: DNS settings
From
: Richard McLane <rsmclane@ncsu.[redacted]>
Date
: Wed, 18 Mar 2009 10:23:47 -0400
Parent
Daniel,
In other words, restart your system :) We spent a week trying to
restart various services depending on the server (ncsd, httpd, cyrus-
imapd, postfix, etc) in an effort to avoid rebooting. Finally we had
to just bite the bullet and do mass reboots. Assuming the down time
isn't an issue, it's less time in the long run.
Richard
On Mar 18, 2009, at 9:20 AM, Will Brockelsby wrote:
> 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
--------------------------------------------------
Richard McLane | Systems Analyst
rsmclane@ncsu.[redacted] | College of Engineering/ITECS
XXX.513.4575 | NC State University
--------------------------------------------------