Forward & Forward only

[Simon Waters]

Halo-wings wrote:
> 
> I am new to DNS (College Student) but I am trying to set up a DNS
> server on free BSD 4.2 using bind 8.2.X but my question is what do the
> forward and forward only commands mean in the configuration file. If
> anyone could point me a web site that might explain this further
> please send me a link. 

The BIND 9 documentation is pretty good even when using BIND 8,
there is a copy at www.isc.org somewhere, or download the source
tar ball for BIND 9 and look in the doc directory for the
Administrator Reference Manual.

forward - basically says pass the query on to another server,
and if that fails try your best to answer it.

forward-only - says pass the query on to another server. With no
attempt to try it yourself.

You typically use "forward" for performance reasons. Say I set
up a group of servers sending mail to e-mail lists, I can run a
local DNS server on each, and forward all requests to a central
DNS which will build a rich cache. If my central server dies,
well things slow down a bit, but the other servers continue
working.

You typically use "forward-only" when a DNS server must resolve
Internet names, but is firewalled to prevent it talking to the
Internet nameservers directly, then queries can be directed to
DNS servers that are able to query the Internet name servers
(Typically in a DMZ area).

Forwarding may also be used on a per zone basis, but the same
effect can usually be achieved by becoming a secondary.