[dns-operations] Spurious (?) DNSSEC SERVFAIL with some (?) versions of BIND for one domain?

[Mark Andrews]

So who is correctly rejecting DS at top of zone at load time?  There is no way
to query for this RRset.

> On 11 Mar 2021, at 06:29, Peter van Dijk <peter.van.dijk at powerdns.com> wrote:
> 
> On Wed, 2021-03-10 at 16:44 +0000, Matthew Richardson wrote:
>>       9qbq9dd8lt1gvge9gdmb5m0o13iuqeqt.prv.se: type NSEC3, class IN
>>>           Name: 9qbq9dd8lt1gvge9gdmb5m0o13iuqeqt.prv.se
> 
> Which is the NSEC3 hash of 'prv.se.',
> 
>>>           Type: NSEC3 (50)
>>>           Class: IN (0x0001)
>>>           Time to live: 3600
>>>           Data length: 43
>>>           Hash algorithm: SHA-1 (1)
>>>           NSEC3 flags: 0
>>>               .... ...0 = NSEC3 Opt-out flag: Additional insecure delegations forbidden
>>>           NSEC3 iterations: 50
>>>           Salt length: 8
>>>           Salt value: 33e9285ab62c0803
>>>           Hash length: 20
>>>           Next hashed owner: 4f848f41f3884a3fc412e821e031cdd8b9a48eca
>>>           RR type in bit map: A (Host Address)
>>>           RR type in bit map: NS (authoritative Name Server)
>>>           RR type in bit map: SOA (Start Of a zone of Authority)
>>>           RR type in bit map: MX (Mail eXchange)
>>>           RR type in bit map: TXT (Text strings)
>>>           RR type in bit map: DS(Delegation Signer)
> 
> which apparently has a DS at the apex of the child zone, which is
> somewhere between 'useless' and 'wrong'.
> 
>>>           RR type in bit map: RRSIG
>>>           RR type in bit map: DNSKEY
>>>           RR type in bit map: NSEC3PARAM
> 
> Combined with
> 
>> 10-Mar-2021 16:20:11.606 dnssec: info: validating _dmarc.prv.se/TXT:
> bad cache hit (_dmarc.prv.se/DS)
> 
> My vague suspicion is that BIND is flagging this as an impossible
> situation, because a DS should live in the parent, and only in the
> parent.
> 
> I recall isc.org 'recently' had a DS at the apex of the child zone; I
> wonder if after ISC removed that, they made BIND, as a validator,
> stricter about it when detected.
> 
> Kind regards,
> -- 
> Peter van Dijk
> PowerDNS.COM BV - https://www.powerdns.com/
> 
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-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742              INTERNET: marka at isc.org