Re: [DNSOP] new ANAME draft: draft-hunt-dnsop-aname-00.txt

Evan Hunt <each@isc.org> Tue, 11 April 2017 20:16 UTC

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Date: Tue, 11 Apr 2017 20:16:16 +0000
From: Evan Hunt <each@isc.org>
To: Florian Weimer <fweimer@redhat.com>
Cc: Peter van Dijk <peter.van.dijk@powerdns.com>, dnsop@ietf.org
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Subject: Re: [DNSOP] new ANAME draft: draft-hunt-dnsop-aname-00.txt
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On Tue, Apr 11, 2017 at 09:11:54PM +0200, Florian Weimer wrote:
> I don't see how you can detect loops without DNS protocol changes.  The 
> query that comes back will look like a completely fresh query.

We can put a limit on the number of hops that are followed in populating
the A and AAAA records for the expanded ANAME response.  If that limit is
exceeded, the ANAME record could be rejected by the auth; either the zone
wouldn't load or address queries return SERVFAIL.

BIND already has a limit of 16 hops for CNAME loop prevention. I assume
other resolver implementations must do something similar.

-- 
Evan Hunt -- each@isc.org
Internet Systems Consortium, Inc.