Reverse DNS RFCs and Recommendations

Wed Oct 30 17:00:37 UTC 2013

On Wed, Oct 30, 2013 at 9:12 AM, Nolan Rollo <nrollo at kw-corp.com> wrote:

> RFC draft-msullivan-dnsop-generic-naming-schemes-00.txt states:
>

I think you mean an "Expired RFC Draft from 2006 written by the people from
SORBS states :"

Which finally brings me to my questions:
> It seems like the unspoken de facto that mail admins appreciate given the
> IP 203.0.113.15 is "203-0-113-15.[type].[static/dynamic].yourdomain.tld".
> This seems perfectly acceptable, it's short, detailed and to the point. Is
> there really anything bad about this?
>

No. Nothing at all, and as you've already discovered it's what is used by
probably the majority of providers that include IP addresses in rDNS.

> What, if any would you name a network, gateway, broadcast address? Should
> the PTR be empty?
>

I've never seen anyone put in rDNS for networks or broadcast addresses.
 (Naming networks was common many years ago, but it never made the jump to
DNS from what I've seen).  rDNS for gateways can be helpful for traceroute,
and there are a few documents that provide examples of naming schemes for
such hosts, but I can't seem to find them right now...  Again, these are
only samples - there's not such thing as a "right" answer.

On Wed, Oct 30, 2013 at 9:24 AM, Nick Hilliard <nick at foobar.org> wrote:

> the only thing that's important is that forward and reverse DNS matches.
> After that, there is no correct or incorrect, so you need to do something
> that makes sense for your deployment.
>

Well, yes and no...  It's true that there's no "correct" answer, but there
are "incorrect" answers - such as putting the term "dynamic" in the rDNS
for an email server. It may not be incorrect enough to break an RFC, but
it's still the wrong thing to do!

  Scott