it tells you domain

ss -lp 'sport = :domain'

expected output

[code lang=text] Netid State Recv-Q Send-Q Local Address:Port Peer Address:Port udp UNCONN 0 0 127.0.0.53%lo:domain 0.0.0.0:* users:(("systemd-resolve",pid=768,fd=12)) tcp LISTEN 0 128 127.0.0.53%lo:domain 0.0.0.0:* users:(("systemd-resolve",pid=768,fd=13)) [/code]