Re: [DNSOP] Delegation into the interior of a zone?

Tony Finch <dot@dotat.at> Wed, 02 January 2019 16:10 UTC

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Date: Wed, 2 Jan 2019 16:09:57 +0000
From: Tony Finch <dot@dotat.at>
To: John Levine <johnl@taugh.com>
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Subject: Re: [DNSOP] Delegation into the interior of a zone?
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John Levine <johnl@taugh.com>; wrote:

> That is, the two zones have the same apex, and NS records point into
> the interior of the second zone, not at the apex.  That works in BIND,
> of course, but it seems wrong.

Well, it kind-of works, but it's brittle.

* If a client queries for the NS records, the authoritative NODATA from
  the child zone will override the delegation NS records (according to
  RFC 2181 trust ranking) which will break future resolution attempts.

* Negative responses from the child zone will have the wrong SOA, causing
  SERVFAIL in the resolver's RFC 2308 response disambiguator.

* DNSSEC will not work at all.

(Any other issues I've forgotten?)

Tony.
-- 
f.anthony.n.finch  <dot@dotat.at>;  http://dotat.at/
Lyme Regis to Lands End including the Isles of Scilly: East or southeast 3 or
4, occasionally 5 at first. Slight or moderate, occasionally smooth in Lyme
Bay. Showers later. Good.