When using DHCP and NetworkManager, the DNS settings are usually obtained from the ISP.
It does not help, when you add your DNS settings to
/etc/resolv.conf (e.g. via
These will be overwritten with the ISP’s DNS, when NetworkManager reconnects.
To disable this behaviour, go to the NetworkManager’s editor (e.g. via
nm-connection-editor) and choose
DHCP, addresses only in the IPv4 settings. There you still can add your DNS addresses below in the
NetworkManager and resolvconf
If you want NetworkManager to use resolvconf settings, create
… as explained in the arch wiki.
Then the DNS settings are applied for all connections and you do not need to keep track of your DNS servers in all your NetworkManager connections.
To enable these global DNS settings, create
/etc/resolv.conf.head with your DNS addresses.
systemctl restart NetworkManager
Make sure that your DNS server supports DNSSEC.
Further information via (German).