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pkaramol
Asked: 2018-01-21 09:08:38 +0800 CST

dns-search vs search option

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What is the difference between the following two entries?

  • dns-search in /etc/network/interfaces

  • search in /etc/resolv.conf

If they serve the same purpose, which one is the recommended to use and how to edit it?

Is there a scenario where one may shadow the other?

networking

1 Answers

  1. Best Answer

    The various dns-* entries in /etc/network/interfaces are used to create corresponding entries in /etc/resolv.conf (depending on what's actually creating /etc/resolv.conf, of course). From the Debian Wiki:

    If the resolvconf program is installed, you should not edit the resolv.conf configuration file manually as it will be dynamically changed by programs in the system. If you need to manually define the nameservers (as with a static interface), add a line something like the following to the interfaces configuration file at /etc/network/interfaces:

    dns-nameservers 12.34.56.78 12.34.56.79

    Place the line indented within an iface stanza, e.g., right after the gateway line. Enter the IP addresses of the nameservers you need to use after dns-nameservers. Put all of them on one line separated by spaces. Don't forget the "s" on the end of dns-nameservers.

    And the Ubuntu LTS Server Guide:

    resolvconf uses DHCP client hooks, and /etc/network/interfaces to generate a list of nameservers and domains to put in /etc/resolv.conf, which is now a symlink:

    /etc/resolv.conf -> ../run/resolvconf/resolv.conf

    To configure the resolver, add the IP addresses of the nameservers that are appropriate for your network in the file /etc/network/interfaces. You can also add an optional DNS suffix search-lists to match your network domain names. For each other valid resolv.conf configuration option, you can include, in the stanza, one line beginning with that option name with a dns- prefix.

    Thus, resolvconf uses these dns-* entries, as well as the configuration from /etc/resolvconf/resolv.conf.d/* to create /etc/resolv.conf.

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