5. Configuring Firewalls
If you run a firewall for your unit, you need to allow outgoing requests to other DNS servers, but you don't need to allow any incoming DNS requests to your servers as no other DNS servers know about your internal names.
|Source Address||Source Port||Dest. Address||Dest. Port|
|Your internal DNS Servers||Any||Any||TCP 53|
|Your internal DNS Servers||Any||Any||UDP 53|