That's a good point. Personally, I'd favour a referral response since it saves resolver a round trip (at least for resolvers not doing QNAME minimisation), it seems in conflict with 3.1.4.1 though as you pointed here.
Marek On Wed, Jan 3, 2018 at 10:31 AM, Peter van Dijk <peter.van.d...@powerdns.com> wrote: > 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/ > > _______________________________________________ > DNSOP mailing list > DNSOP@ietf.org > https://www.ietf.org/mailman/listinfo/dnsop _______________________________________________ DNSOP mailing list DNSOP@ietf.org https://www.ietf.org/mailman/listinfo/dnsop
