Here: on the (non-working) laptop first:
matteo@matteo-laptop:~$ ps fauxw | grep dnsmasq
nobody 4220 0.0 0.0 52868 4180 ? S 22:06 0:00 \_ /usr/sbin/dnsmasq --no-resolv --keep-in-foreground --no-hosts --bind-interfaces --pid-file=/var/run/NetworkManager/dnsmasq.pid --listen-address=127.0.1.1 --cache-size=0 --conf-file=/dev/null --proxy-dnssec --enable-dbus=org.freedesktop.NetworkManager.dnsmasq --conf-dir=/etc/NetworkManager/dnsmasq.d
lxd 2572 0.0 0.0 52868 408 ? S 22:05 0:00 dnsmasq -s lxd -S /lxd/ -u lxd --strict-order --bind-interfaces --pid-file=/run/lxd-bridge//dnsmasq.pid --dhcp-no-override --except-interface=lo --interface=lxdbr0 --dhcp-leasefile=/var/lib/lxd-bridge//dnsmasq.lxdbr0.leases --dhcp-authoritative --listen-address 10.91.84.1 --dhcp-range 10.91.84.2,10.91.84.254 --dhcp-lease-max=252
matteo@matteo-laptop:~$ sudo netstat -lnp | grep 53
[sudo] password for matteo:
tcp 0 0 127.0.1.1:53 0.0.0.0:* LISTEN 4220/dnsmasq
tcp 0 0 10.91.84.1:53 0.0.0.0:* LISTEN 2572/dnsmasq
tcp6 0 0 fe80::b4f8:feff:fe86:53 :::* LISTEN 2572/dnsmasq
udp 0 0 0.0.0.0:5353 0.0.0.0:* 2273/avahi-daemon:
udp 0 0 127.0.1.1:53 0.0.0.0:* 4220/dnsmasq
udp 0 0 10.91.84.1:53 0.0.0.0:* 2572/dnsmasq
udp6 0 0 :::5353 :::* 2273/avahi-daemon:
udp6 0 0 fe80::b4f8:feff:fe86:53 :::* 2572/dnsmasq
unix 2 [ ACC ] SEQPACKET LISTENING 13353 1/init /run/udev/control
And on the (working) desktop:
matteo@matteo-desktop:~$ ps fauxw | grep dnsmasq
nobody 5052 0.0 0.0 52872 2928 ? S 12:34 0:01 \_ /usr/sbin/dnsmasq --no-resolv --keep-in-foreground --no-hosts --bind-interfaces --pid-file=/var/run/NetworkManager/dnsmasq.pid --listen-address=127.0.1.1 --cache-size=0 --conf-file=/dev/null --proxy-dnssec --enable-dbus=org.freedesktop.NetworkManager.dnsmasq --conf-dir=/etc/NetworkManager/dnsmasq.d
lxd 6371 0.0 0.0 49984 2440 ? S 12:35 0:01 dnsmasq --strict-order --bind-interfaces --pid-file=/var/snap/lxd/common/lxd/networks/lxdbr0/dnsmasq.pid --except-interface=lo --interface=lxdbr0 --quiet-dhcp --quiet-dhcp6 --quiet-ra --listen-address=10.30.164.1 --dhcp-no-override --dhcp-authoritative --dhcp-leasefile=/var/snap/lxd/common/lxd/networks/lxdbr0/dnsmasq.leases --dhcp-hostsfile=/var/snap/lxd/common/lxd/networks/lxdbr0/dnsmasq.hosts --dhcp-range 10.30.164.2,10.30.164.254,1h -s lxd -S /lxd/ --conf-file=/var/snap/lxd/common/lxd/networks/lxdbr0/dnsmasq.raw -u lxd
matteo@matteo-desktop:~$ sudo netstat -lnp | grep 53
[sudo] password for matteo:
tcp 0 0 10.30.164.1:53 0.0.0.0:* LISTEN 6371/dnsmasq
tcp 0 0 127.0.1.1:53 0.0.0.0:* LISTEN 5052/dnsmasq
tcp6 0 0 fe80::c836:86ff:fe4b:53 :::* LISTEN 6371/dnsmasq
udp 0 0 0.0.0.0:5353 0.0.0.0:* 4545/avahi-daemon:
udp 0 0 10.30.164.1:53 0.0.0.0:* 6371/dnsmasq
udp 0 0 127.0.1.1:53 0.0.0.0:* 5052/dnsmasq
udp6 0 0 :::5353 :::* 4545/avahi-daemon:
udp6 0 0 fe80::c836:86ff:fe4b:53 :::* 6371/dnsmasq
unix 2 [ ACC ] STREAM LISTENING 49976 8053/dbus-daemon @/tmp/dbus-3AbJiqvg4d
I do see two DNS processes here, but one seems to belong to the NetworkManager, so it is probably not an issue… furthermore, the same situation appears on both machines.