Subject: AXFR open question

From: Edward Lewis <[email-masked]>
Date: Fri, 13 Jun 2008 16:05:53 -0400

While contemplating the specter of "0 message responses" I thought 
about the situation in which a client sends an AXFR query and the 
server kills the connection before any response.

The connection could "die" because of any number of reasons.  Maybe 
the server shutdown its end or maybe some lower layer in the client 
decided the connection was unhealthy and closed its own end.

Should an AXFR client assume that any outstanding queries will never 
be answered?  Should the query ID's be recycled after some long 
period of time (even if the connection is brought back up)?

We talk of an AXFR session, which consists of query and responses.  A 
TCP connection is the transport supporting it.  A session can be 
defined to use multiple transports, in parallel and consecutively 
(wrt time).  Or do we want say that an AXFR session cannot "survive" 
the transport connection servicing it?

And, in the face of a transport going away, is that to be taken as a 
temporary condition and call for a new attempt or say that the client 
ought to take that as something (umm, "more") fatal and not attempt a 
retry?
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Edward Lewis                                                +1-571-434-5468
NeuStar

Never confuse activity with progress.  Activity pays more.

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From: [email-masked] (Andreas Gustafsson)
Date: Mon, 16 Jun 2008 13:45:26 +0300

Edward Lewis wrote:
> be answered?

Yes.

> Should the query ID's be recycled after some long 

The query IDs can be recycled immediately, as they are only 
meaningful within the context of a given TCP connection
(assuming they are used at all).

> (wrt time).

No, not in the case of AXFR.

> Or do we want say that an AXFR session cannot "survive" 

Yes, this is what we should say.

> ought to take that as something (umm, "more") fatal and not attempt a 

This, or any other AXFR error, should cause a retry after the zone's
RETRY interval has passed.

I believe the above reflects the behavior of the three AXFR
implementations I have written as well as one I have read.
-- 
Andreas Gustafsson, [email-masked]

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From: Edward Lewis <[email-masked]>
Date: Mon, 16 Jun 2008 16:36:50 -0400

Thanks for the info.

At 13:45 +0300 6/16/08, Andreas Gustafsson wrote:
...and so on...
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Edward Lewis                                                +1-571-434-5468
NeuStar