Stephane Bortzmeyer <bortzmeyer@nic.fr> writes:
On Thu, Aug 24, 2017 at 10:53:58AM +1000, Mark Andrews <marka@isc.org> wrote a message of 39 lines which said:
If Google was being sensible the servers would just return the information along with the answer. They all support EDNS.
I fully agree with you that NSID (RFC 5001) is great and Google should really deploy it.
+1 for NSID! Should be mandatory for anycast DNS, IMHO. I don't understand why Google haven't enabled it.
However:
e.g. dig +nsid @8.8.8.8
I assume that Google wants also to be debuggable by people who work on inferior operating systems, and have no dig. Hence this trick. For instance, L.root-servers.net has both NSID and a special name, identity.l.root-servers.org (see RFC 7108).
As you state, there is no problem providing both. Or an infinite number of special names if they like. But NSID provides something none of the special names can. Quoting the justification in the intro of RFC5001: Given that a DNS query is an idempotent operation with no retained state, it would appear that the only completely reliable way to obtain the identity of the name server that responded to a particular query is to have that name server include identifying information in the response itself. Sometimes it just isn't enough to know which server answered the previous or next requests. Bjørn