caching-only DNS and forwarders

[Cricket Liu]

> I've set up my caching-only DNS and was left with a question.
> 
> With normal home use of caching-only DNS why should I use the
> "forwarders" option in /etc/named.conf when one just gives it the 
> same DNS listed in /etc/resolv.conf?  The DNS HOWTO (and others)
> have said this is good, but I don't see why. The same external DNS are 
> queried as soon as the local DNS doesn't find the name in its cache
> with or without using forwarding it seems to me.  Is there any test 
> I can do to show what's happening?  I don't like duplicating the IPs 
> in two files if not helpful. Can someone explain better than the HOWTO
> or my "DNS & BIND" book?

How much of "DNS and BIND" did you actually read?

If you only have your resolv.conf file set up like this:

nameserver <local name server>
nameserver <forwarder>

your resolver will only query your forwarder if your local name server
doesn't respond.  In particular, if your local name server tells your
resolver that something doesn't exist, you won't query the next name
server in resolv.conf.  "DNS and BIND" says this clearly in the chapter
on resolvers.

cricket

Acme Byte & Wire
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