DNS Provider to WAN clients

Hi, Just wondering if it is possible to make the XG Firewall a DNS server for WAN? I thought I set it up correctly, however it seems like it only provided for the hosts manually assigned into the firewall, and would not forward unknown requests to the static name servers on the firewall (like it does does LAN ports). Obviously I don't have this open to the entire world, just to some select hosts. I hope not to setup virtual machine just for a DNS server if I don't have to.