How to setup DNS Forwarding ?
The DNS forwarding facility of BIND Version 8 can be used to
create a large site-wide cache on a few servers, reducing traffic over links to external
nameservers. It can also be used to allow queries by servers that do not have direct
access to the Internet, but wish to look up exterior names anyway. Forwarding occurs
only on those queries for which the server is not authoritative and does not have the
answer in its cache. Let us suppose, that we have an internal DNS-2 in the HSZ (High
Security Zone) for the internal hosts and an external DNS-1 in the DMZ (Demilitarized Zone)
for the Internet Access. Using the forwarding feature DNS-2 is able to lookup Internet
hosts, forwarding queries to DNS-1.
Example in named.conf