Ubuntu 16, Bind and disabling ipv6

I furiously tried to convert bind to operate only on ipv4 addresses but no success.

Ubuntu way is to add-4 to OPTIONS at /etc/default/bind9

-> No success After googling I found out the systemd has hijacked the startup and does not use the bind9-config file at all. A proper script to modify is /lib/systemd/system/bind9.service .. […]