Re: [dane] TLSA RRset and CNAME question

John Gilmore <gnu@toad.com> Thu, 14 March 2013 19:21 UTC

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Comments: In-reply-to Viktor Dukhovni <viktor1dane@dukhovni.org> message dated "Wed, 13 Mar 2013 23:53:08 +0000."
Date: Thu, 14 Mar 2013 11:21:06 -0800
From: John Gilmore <gnu@toad.com>
Subject: Re: [dane] TLSA RRset and CNAME question
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> Suppose a query a known signed zone:
> 
> 	Q: _25._tcp.mail.example.com. IN TLSA ?
> 
> and I receive a signed CNAME referral:
> 
> 	A: _25._tcp.mail.example.com. IN CNAME 3.1.1._tlsa.example.edu.

> Is this a a case of "no TLSA records" or "no usable TLSA records"?

This is a case of "no TLSA records".  That's a CNAME record, not a
TLSA record.  If the domain admin wanted to put a TLSA record there,
they know how to do that.

There is nothing magic about the _25._tcp subdomain names.  Using
them for a CNAME (or an A record or anything else) does not indicate
a desire to use TLSA records.

	John