In olden times, we would add entries for name resolution to /etc/resolv.conf and be done with it. Nowadays, with these newfangled scripts that change the configuration all the time, this file simply gets overwritten by a tool/library called resolvconf, so if we want to add something permanently to it, we must do it somewhere else.
Fortunately it’s quite easy, once you know where:
resolfconf uses the directory /etc/resolvconf/resolv.conf.d as the base for its entries. It usually contains three files:
(And sometimes a file called original which contains the original contents of /etc/resolv.conf before resolvconf was installed. This file is ignored.)
To add something permanently, just edit the file “head” and be done with it.
But wait, there is more:
Most likely you don’t want to add the information to “head” but rather add it to the iface entries in the /etc/network/interfaces file. It allows you to add one or more name servers like this:
iface eth0 inet static address 192.168.1.3 netmask 255.255.255.0 gateway 192.168.1.1 dns-nameserver 192.168.1.254 dns-nameserver 18.104.22.168 dns-search foo.org bar.com