Why use Forwarders?

[Joseph S D Yao]

On Thu, Mar 11, 2004 at 02:59:43PM +0000, Oli Comber wrote:
> Hi List,
> 
> I've had problems recently with my bind9 setup where resolution would be
> very slow or not work at all when using Forwarders.
> 
> Now I'm not using them, resolution is fine and dandy and very fast.
> 
> It makes no difference to me whether I use Forwarders or not - I'm on a
> small home network, no need for load balancing. 
> 
> Why would one want to use a forwarder instead of doing a lookup
> directly?
> 
> Does a DNS server have to be set up in a different way to be used as a
> forwarder? 
> 
> Can a server recognise that it is being used as a Forwarder and
> prioritise against that?

Usually, if you are on the public Internet, you should not forward, as
I think everyone has counseled.

If you are behind a firewall that, correctly, blocks all IP flow to the
public Internet, you will have to forward your queries to the firewall
itself [typically] if you want to resolve IP addresses on the public
Internet.  Since you don't have IP connectivity, though, this is often
only done by mail servers to establish validity [or consult ORBS-like
databases], or for sheer monkey curiosity.

Forwarding is also necessary/useful if you are on a private internet
where not all of the DNS maintainers know what they are doing with
regard to NS records, MX records, et al.; or if contamination from DNS
on the public Internet is possible.  [It's better to work to fix both
problems, but it's not always possible.  ;-)]

-- 
Joe Yao				jsdy at center.osis.gov - Joseph S. D. Yao
OSIS Center Systems Support					EMT-B
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