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[DNSOP] Re: ordering of RRSets in the answer section of a DNS response

Robert Edmonds <edmonds@mycre.ws> Wed, 14 January 2026 19:46 UTC

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Date: Wed, 14 Jan 2026 14:45:54 -0500
From: Robert Edmonds <edmonds@mycre.ws>
To: Petr Špaček <pspacek@isc.org>
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Subject: [DNSOP] Re: ordering of RRSets in the answer section of a DNS response
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Petr Špaček wrote:
> Is it 'protocol-legal' to have multiple identical RRs in the message?
> 
> I would think it is not, but also I don't see test prohibiting it.

"...servers should suppress such duplicates if encountered."

(RFC 2181, Section 5)

"A Resource Record Set should only be included once in any DNS reply.
It may occur in any of the Answer, Authority, or Additional Information
sections, as required.  However it should not be repeated in the
same, or any other, section, except where explicitly required by a
specification."

(RFC 2181, Section 5.5)

-- 
Robert Edmonds

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