This option specifies the list of DNS servers that DNS requests will be
forwarded to if they can not be handled by Samba itself.
The DNS forwarder is only used if the internal DNS server
in Samba is used. Port numbers can be appended by separating them from
the address by using a colon (':'). When specifying a port, IPv6
addresses must be enclosed in square brackets ('[' and ']'). IPv6
forwarder addresses with no port specified, don't need the square
brackets, and default to port 53.
192.168.0.1 192.168.0.2 ::1 [2001:db8::1] [2001:db8:1:2::1]:54