ubuntu_dnsmasq
ubuntu_disable_systemd_resolved
ubuntu_iptables_iproute_netpaln

mcedit /etc/resolv.dnsmasq

nameserver 8.8.8.8
nameserver 8.8.4.4

mcedit /etc/resolv.conf

nameserver 127.0.0.1

cp /etc/dnsmasq.conf /etc/dnsmasq.backup

mcedit /etc/dnsmasq.conf

...
port=53
...
resolv-file=/etc/resolv.dnsmasq
...

Перенаправить все DNS запросы на внутренний DNS сервер

mcedit /etc/iptables.sh

...
iptables -t nat --flush
#PREROUTING
iptables -t nat -P PREROUTING ACCEPT
iptables -t nat --flush PREROUTING
iptables -t nat -A PREROUTING -i $int_if -p udp --dport 53 -j REDIRECT --to-ports 53
...

sh /etc/iptables.sh
systemctl enable dnsmasq
systemctl start dnsmasq
systemctl restart dnsmasq
systemctl status dnsmasq
nslookup 8.8.4.4

Очистить кэш dnsmasq

systemctl restart dnsmasq