Why does bind 8.2 need root cache in "forward only" mode?

Kevin Darcy kcd at daimlerchrysler.com
Thu Jun 22 18:51:49 UTC 2000


Carl Mascott wrote:

> I was using bind 8.1.2 as a cache-only server for a small LAN with a dialup
> link to my ISP.  I just tried bind 8.2.2P5 with the same named.conf file and
> discovered that, unlike 8.1.2, it always creates and primes a cache for the
> root zone, even with global option "forward only".  The only zone in my
> named.conf is the reverse zone for 127.0.0 (I use /etc/hosts for my LAN).
>
> Why does bind need a root cache when it is running "forward only"?  In
> "forward only" why should bind ever contact any name server other than one
> of the defined forwarders?
>
> Also, I don't know if it's related, but the new nslookup, unlike the old
> one, causes a dialup every time it is started in interactive mode, before
> any lookup is requested.
>
> I ask these questions because I'd like to avoid unnecessary dialups.
> Thanks!

A design flaw in BIND (IMO), hopefully fixed in BIND 9.

The reason "nslookup" causes a dialup even before you ask it to resolve
anything, is because it's trying to resolve the address of your nameserver into
a name. Real DNS troubleshooting tools, like "dig", don't make unnecessary,
unsolicited lookups like that.


- Kevin





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