Andrew Sullivan <a...@anvilwalrusden.com> wrote: > On Sat, Nov 29, 2014 at 12:06:28PM +1100, Mark Andrews wrote: > > > > A iterative resolver make RD=0 queries. > > A resursive resolver make RD=1 queries. > > The problem with that definition, though I guess it is technically > most accurate, is that it doesn't help anyone who doesn't already > understand the difference. After all, the second of these only says, > "a recursive resolver says that it wants recursion", which is hardly > elicidating for the uninitiated. > > I think Tony's proposal is on the right track (certainly better than > the quick excerpt we did from STD 13, which is at least as confusing). > But I think Paul put his finger on the problem with that text: there's > no way to know in advance what sort of server you're querying.
I think it is worth noting that RFC 1034 talks about the resolution process, i.e. recursive resolution and iterative resolution - it does not talk about iterative resolvers or recursive resolvers. Which sort-of makes sense since whether a resolver is being iterative or recursive is to a large extent a matter of configuration - as Mark said BIND can do both, and this is also true for Unbound, ldns, getdns-api, etc. The exception is pure stub resolvers (e.g. the libc resolver or adns) which can only perform recursive queries. So I think to clarify the terminology, first describe the iterative and recursive resolution processes, and mention the expected values of the RD,RA,AA bits. Then you can describe the distinctions between recursive and iterative clients, and between recursive and authoritative servers, in terms of the roles they play in the different resolution processes. I would say a full resolver is one that contains a cache and is capable of iterative resolution [citation needed]. A stub is (traditionally) cacheless and recursive only. There are intermediate cases - a lot of stubby resolvers have caches. Tony. -- f.anthony.n.finch <d...@dotat.at> http://dotat.at/ Rockall: Southwesterly 4, increasing 5 to 7, occasionally gale 8 in northwest, veering northwesterly 4 or 5 later. Moderate or rough, occasionally very rough later in northwest. Occasional rain. Good, occasionally poor. _______________________________________________ DNSOP mailing list DNSOP@ietf.org https://www.ietf.org/mailman/listinfo/dnsop
