Will said:
In a Windows 2000 AD forest, the child domain controller's DNS is normally
set to add the parent domain as a secondary, just to keep a copy cached for
use locally. What about the forwarders settings in DNS on the child
domain controller? Should this be set to the upstream domain's domain
controller, or does it not matter?
There is no clear cut answer -- it depends on why you
are forwarding and which names you expect to resolve.
For instance: All DNS servers (both zones/domains) on
same LAN with a gateway caching only DNS to the outside
world (The Internet)
ALL DNS servers usually forward to the gateway DNS
Second example: Child DNS at branch site with no independent
Internet access.
It is likely useful to forward to "HQ" DNS servers for Internet
(and other site perhaps) resolution.
You must think through what you will resolve and what the
referral (forwarding, recursion, caching etc) paths will look like.
The goal is:
#1 Resolve EVERYTHING necessary
#2 Do it most efficiently while maintaining rule #1
For #2, try to do it locally, then closest AND/OR try to do
it from the DNS server with the LARGEST cache or broadest
source of information (caching hierarchically for complex
scenarios.)
Then you test, making sure it actually works.