Configuring Linux DNS

There are an incredible number of ways to configure DNS on Linux.

Tailscale attempts to interoperate with any Linux DNS configuration it finds already present. Unfortunately, some are not entirely amenable to cooperatively managing the host's DNS configuration.

Common problems

NetworkManager + systemd-resolved

If you're using both NetworkManager and systemd-resolved (as in common in many distros), you'll want to make sure that /etc/resolv.conf is a symlink to /run/systemd/resolve/stub-resolv.conf. That should be the default. If not,

$ sudo ln -sf /run/systemd/resolve/stub-resolv.conf /etc/resolv.conf

When NetworkManager sees that symlink is present, its default behavior is to use systemd-resolved and not take over the resolv.conf file.

After fixing, restart everything:

$ sudo systemctl restart systemd-resolved
$ sudo systemctl restart NetworkManager
$ sudo systemctl restart tailscaled

DHCP dhclient overwriting /etc/resolv.conf

Without any DNS management system installed, DHCP clients like dhclient and programs like tailscaled have no other options than rewriting the /etc/resolv.conf file themselves, which results in them sometimes fighting with each other. (For instance, a DHCP renewal rewriting the resolv.conf resulting in loss of MagicDNS functionality.)

Possible workarounds are to use resolvconf or systemd-resolved. Issue 2334 tracks making Tailscale react to other programs updating resolv.conf so Tailscale can add itself back.