[DNSOP] 4035 3.1.4.1 erratum? dig ds root-servers.net @X.root-servers.net

["Peter van Dijk" <[e-mail]>]

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/