Re: [dmarc-ietf] Doing a tree walk rather than PSL lookup

Dave Crocker <> Tue, 24 November 2020 18:19 UTC

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From: Dave Crocker <>
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Date: Tue, 24 Nov 2020 10:19:15 -0800
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Subject: Re: [dmarc-ietf] Doing a tree walk rather than PSL lookup
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On 11/24/2020 9:21 AM, John Levine wrote:
> With the tree walk, I was thinking that if the tree walk finds a _dmarc record, that acts
> as the organizational domain, so finance.acme.example can only allow alignment with itself
> or its descendants.
> This is different from the way that OD works now, but the questions are is it worse, and what
> will break if we do it.

Let's consider some attributes, starting with a trivial initial set...

*Accuracy:*       How accurate is the data that gets retrieved?

*Reliability*:    How likely is it that a query will complete successfully?

*Latency:*        How long does it take for a query to complete?

*Vulnerability:*  How easily/likely is it that the service can be 

*Scaling:*        How well does it operate, at Internet scale?

*PSL* *Tree-Walk*

*Accuracy: *       Known problematic        100%

*Reliability:* High                     Mixed

*Latency: * None                     Potentially high

*Vulnerability:*     Generally none           DOS

*Scaling:*           Poor admin, good ops     Good admin, potentially 
poor ops


Dave Crocker

Volunteer, Silicon Valley Chapter
American Red Cross