Reverse range of ip delegation

[Kevin Darcy]

Dusan wrote:

> Hallo all,
> I have a following problem. We have got a range of public IP of class
> C. These 256 IPs were cut into two areas by the router of our
> provider: 1-127 and 128-256 (255.255.255.128). I have to administer
> the second one.
> I do not know exactly how to do a reverse mapping.
> 128.x.x.x.in-addr.arpa is supposedly not correct.
> I was thinking of this:
> $ORIGIN 128.168.192.in-addr.arpa.
> 128-256 NS dns.ourdomain.sk
> would these two lines be enough to correctly delegate it?

I suspect not. That would delegate the
"128-256.128.168.192.in-addr.arpa" subzone.

Nothing starting with "192.168" is "a public IP" anyway. The entire
192.168/16 range is assigned as private, non-routable, RFC 1918
addresses.

What you need to do is a) first understand the structure of the
in-addr.arpa tree (hint: it's hierarchical, like the forward namespace,
but based on octets not netmasks), b) read RFC 2317 to understand how to
"delegate" (really, they mean "alias") a chunk of address space smaller
than a /24, for purposes of DNS maintenance. You could kill both birds
with one stone by getting a copy of the _DNS_and_BIND_ O'Reilly book
(latest and greatest version is Fourth Edition) and reading it through.
Both topics are covered in there.


- Kevin