A name server configured to perform iterative queries with other name servers on the Internet. Forwarders are useful for reducing name resolution traffic and speeding Domain Name System (DNS) name queries for large private TCP/IP internetworks that are connected to the Internet.
They are also used to resolve name queries when a firewall between your network and the Internet prevents clients in your network from directly querying name servers located at your Internet service provider (ISP) or elsewhere on the Internet.
In this case, a typical location for the forwarder is on the bastion host. (The “bastion host” is the host running the proxy server or application layer gateway application.)
If one of your name servers is configured as a forwarder, all off-site queries for resolving DNS names are first sent to the forwarder. The forwarder then performs an iterative query with an off-site name server located at your ISP to resolve the query.
The results of the query are cached by the forwarder. This caching of name query results by the forwarder speeds later name query requests and reduces traffic between your network and the ISP.
Graphic F-19. Forwarder.