Is systemd-resolved essential?

[Tom H]

On Fri, Jul 10, 2020 at 8:08 PM Robert Heller <heller at deepsoft.com>
wrote:
>
> I have several machines on a LAN (some fixed workstations and a
> couple of laptops) all running Ubuntu 18.04. I also have a local
> server on that LAN (presently running CentOS 6) running Bind9
> providing *local* DNS services.
>
> Almost every week when I run the software updates, I have to restart
> systemd-resolved, since for some reason it "forgets" about the local
> DNS server. This is at the very least annoying. I am considering just
> doing 'apt-get purge systemd-resolved' and doing completely without
> systemd-resolved. Is there ANY compelling reason not to do this?

If systemd-resolved is forgetting your LAN's dns server, it might be
worth filing a bug report.

Assuming that you specify a dns server in your connection(s):

Run "systemctl systemd-resolved disable" just in case it's enabled,
but I don't think that it's enabled by default.

Set "dns=default" in "/etc/NetworkManager/NetworkManager.conf" or
"/etc/NetworkManager/conf.d/<filename-that-you-choose>.conf" because
it'll be started by NetworkManager for two reasons; (1)
"dns=systemd-resolved" is set in "/usr/lib/NetworkManager/conf.d" and
"/etc/resolv.conf" is a symlink to a systemd-resolved-managed
"resolv.conf".

Change the "/etc/resolv.conf" symlink to point at
"/run/NetworkManager/resolv.conf".