Classical problem when Bind9 does’t start up automatically, and there are missing allows for DNS in iptables…

Workarounds:

Iptables restore:

iptables -I INPUT -p udp -m udp --dport 53 -j ACCEPT
iptables-save > /etc/firewall.conf
vim /etc/network/if-up.d/iptables
~
#!/bin/sh
iptables-restore < /etc/firewall.conf
~
chmod +x /etc/network/if-up.d/iptables

Bind9 autostart:

update-rc.d bind9 defaults
update-rc.d bind9 enable

ufw disable
reboot