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Stephen Ostermiller
Asked: 2016-04-09 10:38:40 +0800 CST

resolveconf -u keeps adding an unwanted search domain to resolve.conf

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I have my desktop computer configured with a static IP address:

However, /etc/resolve.conf keeps getting overwritten with:

nameserver 127.0.0.1
search localdomain example.com

This seems to happen periodically or when I run sudo resolvconf -u.

I would really like to get example.com removed from the dns search domain list. I used to have it in there but its causing problems now. I just can't seem to get it out. I don't know where it is coming from or why it keeps getting put back. As far as I can grep, there is nothing referring to example.com anywhere in my /etc directory anymore.

What is putting this search domain into my resolv.conf file and how can I prevent it from doing so?

dns

3 Answers

  1. For ipv4, @stalet's suggestion to edit /etc/dhcp/dhclient.conf should work; also try removing domain-search and domain-name from the request. Verify the settings worked in /var/lib/NetworkManager/dhclient-[connection-uuid]-[ifname].lease.

    However, the unwanted search domain may be coming from the ipv6 dhcp server, as I found on 16.04/Xenial. If NetworkManager's dhclient -6 command succeeds and the dhcp server sets search domains, NetworkManager will merge those into the ipv4 search domain list.

    A simple way to fix this on a connection-by-connection basis is to configure the connection's ipv6 settings to "Method: Automatic, addresses only" or even "Method: Ignore".

    Setting this for each connection could become annoying, and I looked pretty hard but couldn't find a way to fix this globally. Adding supersede dhcp6.domain-search to and removing request dhcp6.domain-search from /etc/dhcp/dhclient.conf doesn't seem to help. Also, copying that file to /etc/dhcp/dhclient6.conf caused NetworkManager to correctly template it to /var/lib/NetworkManager/dhclient6-[ifname].conf, but NetworkManager insists on adding also request dhcp6.domain-search;, and the unwanted search domain is still added.

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  2. The search content is provided by dhcp, and can be overridden in /etc/dhcp/dhclient.conf by supersede these variables with empty values.

    Add these lines at the bottom of the /etc/dhcp/dhclient.conf

    supersede domain-name "";
supersede domain-search "";
supersede search "";

    To make the change affect your system you can reconnect to your network or just restart the network-manager service.

    sudo service network-manager restart
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  3. I saw an update to resolveconf 1.78ubuntu5 today (https://launchpad.net/ubuntu/xenial/+source/resolvconf/+changelog), referencing this Launchpad bug, https://bugs.launchpad.net/maas/+bug/1711760. Perhaps this issue is resolved now?

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