[dns-operations] DNAME interoperability

Edward Lewis Ed.Lewis at neustar.biz
Tue Nov 29 22:35:09 UTC 2011

At 18:36 +0000 11/29/11, Tony Finch wrote:
>Possibly of interest to this list, I've posted an article on my blog
>describing a couple of DNAME interoperability problems that we have
>encountered. Has anyone else seen anything similar?

After writing what follows, I realize it isn't an "interoperability 
problem" per se, but that the two implementations send back different 
answers to the same question each of which is not strictly what the 
(unclear) spec says to do.

I raised an issue related to the TWNIC case you refer to on an IETF 
list a few weeks ago.


Something minor, it seems that while the specs (unclearly) say that 
when processing a CNAME/DNAME the response concludes when you leave 
the zone.  But BIND will, under some circumstances, include the 
records from the target zone and NSD will include some of the records 
from the target zone.  Both differ from a strict reading from the 
(unclear) spec in different ways.  But all of the variations are 
coherent so there's no operational evidence this is a problem.

(I've kept this terse.  Saying BIND and NSD differ shouldn't be taken 
as "the sky is falling" it's a case of two popular implementations 
doing slightly different things.)

Is this what you had in mind?
Edward Lewis
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