resolvconf

Update DNS configuration

$ resolvconf -u

$ echo "nameserver 8.8.8.8" | resolvconf -a [eth0]

$ resolvconf -d [eth0]

$ resolvconf -l

$ cat /etc/resolv.conf

resolvconf [-a interface] [-d interface] [-u] [options]

resolvconf manages /etc/resolv.conf dynamically. It aggregates DNS configurations from multiple sources.
Interfaces register their DNS servers. DHCP, VPN, and NetworkManager contribute.
Priority ordering determines final configuration. Earlier interfaces have higher priority.
The generated resolv.conf combines all inputs. Head and tail files add static content.
Deletion removes interface contribution. Useful when connection terminates.

-a INTERFACE

Add/update interface config.

Delete interface config.

Update resolv.conf.

List interfaces.

Include interfaces.

Exclude interfaces.

Show head file.

May conflict with systemd-resolved. Distribution implementations vary. Some use openresolv, others resolvconf.

resolvconf was created to handle dynamic DNS configuration from multiple network sources. Various implementations exist including openresolv and the Debian resolvconf package.

systemd-resolved(1), dhclient(1), nmcli(1)