[svlug] Domains and IP's

[George Bonser]

THere are two ways to do this. One is to assign each IP address a hostname
from your domain. The problem with this is that you do not control the
reverse DNS in the in-addr.arpa domain that is controlled by the true
owners of the IP addresses, your relatives' ISPs. A reverse lookup will
come up with a different hostname that a forward lookup.

relative1.domain.com.	IN A 123.12.123.12

but

12.123.12.123.in-addr.arpa. IN PTR some-other-name.isp.com

There are two ways around this:

1. IPIP tunneling where their machines have two IP addresses, the one the
ISP assigns and one you give them from your address space. The drawback is
that all their traffic flows through your pipe.

2. Have their ISP cooperate. They need to add two records in their
nameserver and you need to create a bogus in-addr.arpa domain.

They add:

jav-bogus.123.12.123.in-addr.arpa. IN NS <your-nameserver>

Then in their in-addr.arpa zone, they put:

12.123.12.123.in-addr.arpa. IN CNAME 12.jav-bogus.123.12.123.in-addr.arpa.

In your nameserver, you serve the bogus domain and have a record that
looks like:

12.jav-bogus.123.12.123.in-addr.arpa.	IN PTR relative1.domain.com.

Assuming that each relative is on a different network, you will need to
set up a bogus domain for each and fine a cooperative ISP for each.

The way this works is a site trying to find a hostname for
12.123.12.123.in-addr.arpa. will find a CNAME pointing to your bogus
domain. It finds your nameserver as being listed for the bogus domain and
asks your nameserver for the PTR record the bogus CNAME points to and gets
the hostname. Bingo, they can now ftp to uu.net!


On Tue, 17 Nov 1998, Javilk wrote:

> 
>      Say I have two sites, one on one side of the continent, and another
> on the other side; or perhaps on another continent.  Both, or all, of the
> sites are run by relatives, and want a common domain name. For generality,
> let's call the domain smith.com.
> 
>      Is there a simple way to have a tom.smith.com at one site, and
> dick.smith.com at another site, and harry.smith.com at another site?  Or
> do all the smith.com computers have to effectively be at common
> hierarchical class of IP addresses located at a common routing endpoint? 
> 
>      (As in, I have some relatives...  I want to hook them on Linux.  I
> don't want to battle them over our name.)
> 
> - javilk at mall-net.com -----------------------------
> -------- MS asks "Where do you want to go?" -------
> ------- Linux asks "What do you want to do?" ------
> -- It is doers, not goers, who built this world! --
> --------- Member: http://www.svlug.org/ -----------
> 
> 
> --AAA20527.911291486/polly.mall-net.com--
> 
> 
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George Bonser

The Linux "We're never going out of business" sale at an FTP site near you!


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