[CentOS] DNS update system-config-network GUI

Robert Spangler mlists at zoominternet.net
Thu Nov 18 12:07:53 EST 2010


On Thursday 18 November 2010 07:09, Lanny Marcus wrote:

>  Box is fully updated CentOS 5.5 (32 bit). DHCP is from the ADSL modem
>  192.168.1.1. After I update the DNS settings and restart the network,
>  the DNS changes do not hold. I have tried using this GUI, as a regular
>  user, after giving the root password, and, also, logged in as the root
>  user.

DHCP will always over write the resolv.conf file when started.

>  When I begin, the Primary DNS is shown as 192.168.1.1 the IP of the
>  ADSL modem. I move that IP to the Tertiary DNS and insert the Primary
>  and Secondary DNS IP's I want to use. Then, I save the file, quit, and
>  restart the network (service network restart). I see messages that the
>  file has been saved and suggesting that I restart the network or the
>  box.

You don't have to restart the network once you have edited resolv.conf file.  
This file is probed every time you use DNS so once you have changed and saved 
it your changes will take effect.

>  The DNS I want to use is that of OpenDNS.com and I saw it work,
>  briefly.Then,it stops working and when I launch the
>  system-config-network GUI  again, I see it has reverted to the
>  original configuration, with only the Primary DNS of 192.168.1.1 (the
>  ADSL modem) shown.

That is because of what I first posted, DHCP overwrites the resolv.conf file.

>  Questions: The "DNS Search Path" is blank. Is there something I should
>  insert there?

Not sure I do not use GUI programs to configure my system.

>  If it appears that I am using the system-config-network GUI properly,
>  what configuration file can I modify, to make these DNS changes hold
>  permanently?

As long as you are using DHCP you are going to have this issue.  What I can 
suggest is the following in preferred order;

1. Edit the DHCP server to give out the DNS Server you want to use.

2. Buy a Cisco/Linksys Router/Switch and place that between the ADSL and your 
machine and set it up to give out the DNS servers you want to use.

3. Create a file myresolv.conf with the setup the way you want and then at the 
end of rclocal put in a line to copy myresolv.conf to resolv.conf.

I am sure there are other ways of doing this but if this is a laptop then you 
really don't want to make any changes to anything but the DHCP Server as when 
you move from location to location you could prevent your laptop from 
functioning properly.


-- 

Regards
Robert

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