[lug] DNS and a thanks for the DSL info.

[Sean Reifschneider]

On Sun, Aug 27, 2000 at 06:11:41PM +0200, rm at mamma.varadinet.de wrote:
> take the IP-Address as expressed in qaudruples and split it up
> 192.168.2.1 =>  192  168  2  1
>
> take away the 'Host' parts

You don't drop the host part if you're looking up the address...  You only
drop that when searching for an authority.  So, given
1.2.168.192.in-addr.arpa, your resolver would first try looking that up,
then would start looking for 2.168.192.in-addr.arpa, 168.192.in-addr.arpa,
until it found somone who knew where to get those records.

> 192 168 2 1  => 192 168 2 (attention: this works only if your netmask uses a 
>                            multiple of 8, i.e. is a class A/B/C net)

That's because DNS can't really search for all possible combinations of
what an unusual mapping might be.  It just drops components until it finds
somone who will resolve the domain.

So, if you have a /28, your ISP *SHOULD* be able to delegate your
records to your server using a trick.  Otherwise you have to get your
ISP to deal with reverse DNS changes.

> 192 168 2 => '2.168.192.inet-addr.arpa.'

I think you mean "in-addr.arpa".

Sean
-- 
 Use more honey!  Find out what she knows.
                 -- _Buckaroo_Banzai_
Sean Reifschneider, Inimitably Superfluous <jafo at tummy.com>
tummy.com - Linux Consulting since 1995. Qmail, KRUD, Firewalls, Python