reverse resolution failing

[Warren Kumari]

On Feb 7, 2013, at 12:51 PM, Tony Finch <dot at dotat.at> wrote:

> Jim Pazarena <bind at paz.bz> wrote:
>> 
>> while it can resolve "webmail.acrodex.com" ( 139.142.184.10 )
>> it cannot reverse resolve 139.142.184.10
> 
> They are using classless reverse DNS, which is fine except that the
> nameservers for the target zone are very broken.
> 
> 10.184.142.139.in-addr.arpa. CNAME 10.0-25.184.142.139.in-addr.arpa.
> 
> 0-25.184.142.139.in-addr.arpa. NS pluto.acrodex.com.
> 0-25.184.142.139.in-addr.arpa. NS nova.acrodex.com.
> 0-25.184.142.139.in-addr.arpa. NS saturn.acrodex.com.
> 
> Nova does not exist.
> 
> Pluto refuses most questions for 10.0-25.184.142.139.in-addr.arpa except
> if you ask for a PTR, in which case it replies with a bogus question
> section containing 139.0.184.142.in-addr.arpa.
> 
> Saturn works OK for most questions, and returns a PTR record if you ask
> for ANY, but if you request a PTR directly it ignores you.

Hmmm…

So, for many years I've wondered this. I've looked a little myself, and spoken to a few folk, but never gotten a really satisfactory answer -- maybe there just isn't one…

You often see freaky things like the above (actually, this one is only somewhat freaky), where nameserver implementation behave in bizarre / insane manners. For many of these it seems as through the NS is simply bored, and misbehaving for entertainment purposes ("Whhheee! I'll reply to all A queries with TXT answers, lets see what they make of that!", or, my favorite, "Whatever folk ask, I'll reply with a cname containing the query name, but with alternate labels swapped...…").
For example, even if I tried (well, without much hacking) I cannot figure out how to duplicate Saturn's behavior…

What is it about the DNS protocol that leads to this? Do folk look at all the existing auth server offerings and decide "No, don't like those, I'll just write my own… in haskel!"?
Or is is simply that nameservers themselves are malicious bastards? Are they all conspiring against us? Is there some very subtle joke that we are not seeing?

W



> 
> Tony.
> -- 
> f.anthony.n.finch  <dot at dotat.at>  http://dotat.at/
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