John, ----- Original Message -----
From: "John Heidemann" <johnh@isi.edu> To: "Warren Kumari" <warren@kumari.net> Cc: "rssac-caucus" <rssac-caucus@icann.org> Sent: Tuesday, 18 October, 2016 01:47:35 Subject: Re: [rssac-caucus] NSID support on the root-servers
[...]
But I was trying to figure out if the method matters (NSID vs CH TXT). Is there any practical technical advantage NSID has over CH TXT. (Context: to determine if we should have NSID for the anycast latency work I described at DNS-OARC.)
Suzanne Woolf suggested that NSID wins because you can BOTH answer another query (say, SOA) AND find out the server that replied to you. This statement *is* in the abstract of rfc-5001, but because it doesn't say why CH TXT cannot do provide query reply and site in one bundle, it's easy to miss.
For mapping catchments, though, this advantage doesn't matter at all. The only information you want is the site; you have no other query to make.
No, the strong reason for NSID is exactly what you said in previous argument. You want to know how the particular instance of DNS server replied to you. Consecutive queries with f.e. "IN SOA" and "CH TXT" doesn't guarantee you that due to the nature of anycast routing.
And, at least for now, a practical argument against NSID is that it is not supported across all Root Letters.
I don't agree, that's a practical argument to _get_ it supported across all Root letters.
(* Caveat: Let's just stipulate that NSID is attractive is because it is the New Hotness, and clearly CH TXT is Old And Busted. And least as evidenced by the larger RFC number and absence of an implementation-specific qname.)
"New Hotness" as in 9+ years? I understand a certain conservatism across root servers deployment, but at the same time the Root servers should be a "showcase" of DNS technology. And it's 9+ years (August 2007) since NSID become RFC. Cheers, -- Ondřej Surý -- Technical Fellow -------------------------------------------- CZ.NIC, z.s.p.o. -- Laboratoře CZ.NIC Milesovska 5, 130 00 Praha 3, Czech Republic mailto:ondrej.sury@nic.cz https://nic.cz/ --------------------------------------------