Use DNS zone forwarding instead of the forwarding option if you want to forward queries for different domain names to different DNS servers according to the specific domain names contained in the queries.
Setting the forwarder deployment role at the zone level creates a corresponding forwarding zone on a DNS server and enables conditional forwarding on a Windows DNS server. Forwarding zones can speed up the recursion process, because a query is sent directly to the server hosting the authoritative zone without needing to contact the root servers. Forwarding zones can also be used effectively if you need to forward queries to a DNS server that is not otherwise accessible on the Internet, perhaps at the other end of a virtual private network connection.
Note: Recursion is automatically enabled when you deploy a forwarder deployment role. You need to create an external server to represent the DNS server to which you will be forwarding.