Output edited for brevity:
$ dig ds root-servers.net @d.root-servers.net
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 17643
;; flags: qr aa rd; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1
;; WARNING: recursion requested but not available
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;root-servers.net. IN DS
;; AUTHORITY SECTION:
root-servers.net. 3600000 IN SOA a.root-servers.net.
nstld.verisign-grs.com. 2017111600 14400 7200 1209600 3600000
$ dig ds root-servers.net @e.root-servers.net
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 26972
;; flags: qr rd; QUERY: 1, ANSWER: 0, AUTHORITY: 13, ADDITIONAL: 27
;; WARNING: recursion requested but not available
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;root-servers.net. IN DS
;; AUTHORITY SECTION:
net. 172800 IN NS a.gtld-servers.net.
net. 172800 IN NS b.gtld-servers.net.
.. ..
;; ADDITIONAL SECTION:
a.gtld-servers.net. 172800 IN A 192.5.6.30
b.gtld-servers.net. 172800 IN A 192.33.14.30
.. ..
When running the query in the Subject, these are the two possible
outputs I have observed from various root servers (with some variation
from the same letter, presumably because of dual vendor strategies).
From 4035 3.1.4.1, the NODATA response should be sent when:
o The name server has received a query for the DS RRset at a zone
cut.
o The name server is authoritative for the child zone.
o The name server is not authoritative for the parent zone.
o The name server does not offer recursion.
Points 1, 2 and 4 are clear. It is point 3 that hurts here. The root
servers are authoritative for root-servers.net. and for . , but not for
net - and they know this because they can see the delegation in the root
zone.
It is my suspicion that 3.1.4.1 was not written with this edge case in
mind, and I think that while 3.1.4.1 favours the NODATA response, the
referral is much more useful. As a data point, the PowerDNS validator
currently gets in trouble with the NODATA response:
https://github.com/PowerDNS/pdns/issues/6138
I think an erratum to 4035 is in order, clarifying the language such
that servers would return the referral in this case. I have not figured
out the exact wording yet (but I will).
What does dnsop think?
Kind regards,
--
Peter van Dijk
PowerDNS.COM BV - https://www.powerdns.com/
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