Re: [DNSOP] Fundamental ANAME problems

Richard Gibson <richard.j.gibson@oracle.com> Fri, 02 November 2018 21:00 UTC

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To: Bob Harold <rharolde@umich.edu>, Brian Dickson <brian.peter.dickson@gmail.com>
Cc: IETF DNSOP WG <dnsop@ietf.org>
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From: Richard Gibson <richard.j.gibson@oracle.com>
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Date: Fri, 2 Nov 2018 17:00:47 -0400
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Subject: Re: [DNSOP] Fundamental ANAME problems
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I haven't reviewed the full draft yet, but am happy to see some people 
echoing my sentiments from earlier versions [1]. I particularly wanted 
to agree with some statements from Bob Harold.

On 11/2/18 15:20, Bob Harold wrote:
> Another option to give users is a non-updating fallback A record, that 
> could point to a web redirect.  That saves all the hassle of updates.

YES! This means a slightly worse fallback-only experience for users 
behind ANAME-ignorant resolvers that query against ANAME-ignorant 
authoritatives (the introduction of ANAME awareness to /either/ 
component allowing an opportunity to provide better address records by 
chasing the ANAME target), but provides a dramatic reduction in the 
amount of necessary XFR traffic. And even more importantly, it forces 
TTL stretching to be an explicit decision on the part of those 
administrators who choose to perform manual target resolution and update 
their zones to use them as fallback records (as they would do now to 
approximate ANAME anyway), rather than an inherent and enduring aspect 
of the functionality.

Treating ANAME-sibling address records as fallback data also supports 
better behavior for dealing with negative results from resolving ANAME 
targets (NODATA, NXDOMAIN, signature verification failure, response 
timeout, etc.)—serve the fallbacks.

> My preference would be a *NAME record that specifies which record 
> types it applies to.  So one could delegate A and AAAA at apex to a 
> web provider, MX to a mail provider, etc.  That would also be valuable 
> at non-apex names.  But I am happy to support ANAME as part of the 
> solution.
I agree on both counts (arbitrary type-specificity and deferment to a 
later date).


[1]: https://www.ietf.org/mail-archive/web/dnsop/current/msg21722.html