Re: [DNSOP] Tell me about tree walks

Tony Finch <dot@dotat.at> Wed, 11 November 2020 22:23 UTC

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Date: Wed, 11 Nov 2020 22:23:03 +0000
From: Tony Finch <dot@dotat.at>
To: John R Levine <johnl@taugh.com>
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Subject: Re: [DNSOP] Tell me about tree walks
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John R Levine <johnl@taugh.com> wrote:
>
> > One possible way for DMARC to mitigate it would be to walk *down* instead
> > of up, and (in the application, not relying on the recursive server) stop
> > on NXDOMAIN because RFC 8020 tells you this is sensible, otherwise take
> > the last result you find.
>
> I wouldn't want to skip the cache.  In most settings there's a whole lot of
> mail from the same place and most of the answers are likely to be cached.
> Perhaps just note that if you're worried about this, use a cache the does RFC
> 8020.

Ah oops, I was too terse: I meant, use the recursive server as usual, but
don't assume it implements RFC 8020: instead (re-)do the NXDOMAIN logic in
the application.

Tony.
-- 
f.anthony.n.finch  <dot@dotat.at>  http://dotat.at/
Trafalgar: In southeast, easterly 4 to 6. In northwest, southwesterly 5 to 7,
becoming cyclonic 4 or 5 later. In southeast, moderate. in northwest, moderate
becoming rough. In southeast, fair. In northwest, showers. Good.