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Re: [DNSOP] draft-tale-dnsop-serve-stale

Jared Mauch <jared@puck.nether.net> Mon, 27 March 2017 22:56 UTC

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From: Jared Mauch <jared@puck.nether.net>
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Date: Mon, 27 Mar 2017 18:55:36 -0400
Cc: paul vixie <paul@redbarn.org>, dnsop@ietf.org, Dave Lawrence <tale@dd.org>
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To: Robert Edmonds <edmonds@mycre.ws>
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Subject: Re: [DNSOP] draft-tale-dnsop-serve-stale
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> On Mar 27, 2017, at 6:46 PM, Robert Edmonds <edmonds@mycre.ws> wrote:
> 
> Jared Mauch wrote:
>> IOn Mar 27, 2017, at 5:59 PM, P Vix <paul@redbarn.org> wrote:
>>> 
>>> I agree to review and comment. Note that I am provisionally negative to the idea itself, and my review may reflect that. Vixie
>> 
>> 
>> I will note there are other implementations out there as well, such as in unbound.  serve-expired configuration directive is available there as well.
> 
> Though, the algorithm described in this document is a much different
> algorithm than the one in Unbound.

At least the initial implementation is documented (via code) here:

https://github.com/jedisct1/unbound/commit/e03d89343e4031be15b2ee78bd432f83cdc79889


> If I understand Unbound's serve-expired algorithm correctly, it always
> serves from cache if available (regardless of expiration status), and if
> what it served to the client happened to be expired, it triggers a
> post-response fetch to update the cache asynchronously. That can end up
> serving a lot more stale bread than is strictly necessary if your
> Unbound server only serves a few clients.

I see the perceived damage here as very low due to the "few clients" you already
commented on.

- Jared

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