[Pdns-users] Strange pdns SOA results * 2

Lorens Kockum lorens-pdns-3987 at tagged.lorens.org
Thu Feb 2 22:44:26 UTC 2006

On Thu, Feb 02, 2006 at 10:39:39PM +0100, Christopher Arnold wrote:
> I just noticed that the zone frankpr.se had the following entry:
> 	CNAME	web.infotropic.com
> Since this isnt a legal entry i gave it a try to change to an A record 
> instead. Switched on recursion and problem dissapeared...

CNAMEs are dark and scary magic, and unconventional CNAMEs can
be quite interesting.  On someone else's servers.

Basically a CNAME says that this record is totally identical
to another record. For *everything*, not just for an A record,
which is why it isn't legal to have other records beside a


	frankpr.se CNAME   web.infotropic.com

means that the SOA for frankpr.se is that of web.infotropic.com,
which doesn't have one, so you certainly got a *zero-record*
answer, with the SOA of infotropic.com as authority for
that.  Same thing for NS.

Using this explanation, I think you will be able to explain to
your satisfaction all the bizarre results you had.

Did this setup actually work (apart from .se not liking it)?
You would have had a rude awakening when you found postfix
*rewriting* the destination e-mail address chris at frankpr.se to
chris at web.infotropic.com *before* attempting delivery by SMTP to
the IP address (since web.infotropic.com doesn't
have an MX).

There *could* exist some kind of "A referral" record that says
that to obtain an A record for this name one should take the A
record of the content of the referral record, a CNAME just for
A records if you like, but there is none (and I'm not certain
there should be).  CNAMEs can be a substitute, but with some
very rough edges :-)


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