Re: [DNSOP] Fw: New Version Notification for draft-yao-dnsop-root-cache-00.txt

Robert Edmonds <edmonds@mycre.ws> Wed, 28 October 2015 22:39 UTC

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Date: Wed, 28 Oct 2015 18:39:22 -0400
From: Robert Edmonds <edmonds@mycre.ws>
To: Bob Harold <rharolde@umich.edu>
Message-ID: <20151028223922.GA7699@mycre.ws>
References: <201509291227269136613@cnnic.cn> <20150929092049.4d005a16@casual> <CA+nkc8DExG8=hpJzmE8qmjbsj3njzVGQFNH5aXwEgUrG6GgE6g@mail.gmail.com>
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Cc: Shane Kerr <shane@time-travellers.org>, Jiankang Yao <yaojk@cnnic.cn>, dnsop <dnsop@ietf.org>
Subject: Re: [DNSOP] Fw: New Version Notification for draft-yao-dnsop-root-cache-00.txt
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Bob Harold wrote:
> Reading these various ideas brings up a question in my mind.  If a server
> queries for the SOA of a zone and the serial number has not changed, can it
> then assume that all of the entries in its cache for that zone should still
> be valid now, and for the their original TTL value starting now?  If the
> values had changed, wouldn't the serial # also change?  Seems like I must
> be missing something here.

No inferences like that can be drawn based on the SOA SERIAL field,
because the serial number may have wrapped around to the same value that
was observed previously.  (Even if the time between queries is very
small, there is still a finite window of time during which the zone
publisher can fit as many zone updates into as needed -- at least
conceptually.)

-- 
Robert Edmonds