Subject: [dnsext] AXFR Clarify -- open issue w/ 'zone loading'

From: Alfred Hönes <[email-masked]>
Date: Fri, 5 Sep 2008 01:13:06 +0200 (MESZ)

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At the DNSEXT session in Dublin, the WG has committed to submit
text proposals for draft-ietf-dnsext-axfr-clarify-09, to address
the discussion point of 'AXFR operation' vs. 'Zone loading'.

Here is my proposal:

Add a new first paragraph to Section 6, "Zone Integrity" :

   An AXFR client MUST ensure that only a successfully transferred
   copy of the zone data can be used to serve this zone.  Previous
   description and implementation practice have introduced a two-stage
   model of the whole zone synchronization procedure: Upon a trigger
   event (e.g., polling of SOA resource record detects change in the
   SOA serial number, or via DNS NOTIFY [RFC1996]), the AXFR session
   is initiated, whereby the zone data are saved in a zone file or
   data base (this latter step is necessary anyway to ensure proper
   restart of the server); upon successful completion of the AXFR
   operation and some sanity checks, this data set is 'loaded' and
   made available for serving the zone in an atomic operation, and
   flagged 'valid' for use during the next restart of the DNS server;
   if any error is detected, this data set MUST be deleted, and the
   AXFR client MUST continue to serve the previous version of the zone,
   if it did before.  The externally visible behavior of an AXFR client
   implementation MUST be equivalent to that of this two-stage model.

Kind regards,
  Alfred.

-- 

+------------------------+--------------------------------------------+
| TR-Sys Alfred Hoenes   |  Alfred Hoenes   Dipl.-Math., Dipl.-Phys.  |
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