Classless in-addr.arpa delegation.

Kevin Darcy kcd at daimlerchrysler.com
Mon Aug 28 22:31:03 UTC 2000


Wait a minute! What zone are those PTR's contained in? The C-class
zone? That's *bad*news*. Not only are you blinding your own clients to other
PTR's in that same C-class range, but you're propagating bogus Authority
Section data, thus potentially blinding *other*people's* nameservers to other
PTR's in that same C-class range, not to mention misdirecting traffic to your
nameservers.

There's a reason that RFC 2317 is a BCP.


- Kevin

Jay Nugent wrote:

> Greetings,
>
> On Mon, 28 Aug 2000, Kevin Darcy wrote:
>
> >
> > Doing RFC 2317 on a non-bit-boundary is a little unusual, but certainly
> > workable.  That's why I say that "classless delegation" is somewhat of a
> > misnomer -- it's really *aliasing* rather than "delegation" _per_se_.
> > All your ISP needs to do is add 10 CNAMEs to the
> > 192.204.212.in-addr.arpa zone:
> >
> > 51    in    cname    51.rev.jdimedia.nl.
> > 52    in    cname    52.rev.jdimedia.nl.
> > 53    in    cname    53.rev.jdimedia.nl.
> > (etc.)
> >
> > I've used "rev.jdimedi.nl" here as the "container" zone for the PTR
> > records, but you could use *anything* mutually-acceptable between your
> > and your ISP, as long as it's a zone delegated to, and controlled by
> > you.
>
>    Or just have the ISP do the following which will send all PTR lookups
> to YOUR nameserver.  Then on your nameserver you use conventional PTR
> records to do the final resolve.
>
> At the ISP:
> -----------
> 51    IN     NS     ns1.yourserver.com.
> 52    IN     NS     ns1.yourserver.com.
> 53    IN     NS     ns1.yourserver.com.
>
> In your nameserver:
> -------------------
> 51    IN     PTR    larry.yourdomain.com.
> 52    IN     PTR    moe.yourdomain.com.
> 53    IN     PTR    curley.yourdomain.com.
>
>    I do this for my 128-host address block.  My ISP didn't even know it
> could be done.  They learn something new from their customers every day
>   :-)
>
>       --- Jay
>
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