диспетчер разрешения сетевых имен (Network Name Resolution manager)
Сигналы (Signals)
SIGUSR1
Upon reception of the SIGUSR1 process signal systemd-resolved
will dump the contents of all DNS resource record caches it
maintains, as well as all feature level information it learnt
about configured DNS servers into the system logs.
SIGUSR2
Upon reception of the SIGUSR2 process signal systemd-resolved
will flush all caches it maintains. Note that it should
normally not be necessary to request this explicitly – except
for debugging purposes – as systemd-resolved flushes the
caches automatically anyway any time the host's network
configuration changes. Sending this signal to
systemd-resolved is equivalent to the resolvectl flush-caches
command, however the latter is recommended since it operates
in a synchronous way.
SIGRTMIN+1
Upon reception of the SIGRTMIN+1 process signal
systemd-resolved will forget everything it learnt about the
configured DNS servers. Specifically any information about
server feature support is flushed out, and the server feature
probing logic is restarted on the next request, starting with
the most fully featured level. Note that it should normally
not be necessary to request this explicitly – except for
debugging purposes – as systemd-resolved automatically
forgets learnt information any time the DNS server
configuration changes. Sending this signal to
systemd-resolved is equivalent to the resolvectl
reset-server-features command, however the latter is
recommended since it operates in a synchronous way.
