DNS Tools



Resolv.conf

Confguration is updated by various programs in /etc/resolv.conf. This is managed by systemd-resolved and will get cached & overwritten when pursuing activities like vpn.

Monitoring

One problem-to-solve is ‘Who has last written to that file?’

# The following command lists the most recent activity and monitors (-f, follow) it for incoming activity $ sudo journalctl -u systemd-resolved -f

To get additional verbosity (debug) information on the channel, you’ll need to reconfigure and restart the resolved daemon:

[Service] Environment=SYSTEMD_LOG_LEVEL=debug

into the override.conf of systemd-resolved via

sudo systemctl edit systemd-resolved

Restart to take effect:

See also: unix.stackexchange:how-to-troubleshoot-dns-with-systemd-resolved.