Jelte Jansen <jelte.jan...@sidn.nl> wrote: > On 01/05/2015 05:55 PM, Bob Harold wrote: > > > > I would expect "www.something..." to be in the same zone as > > "something..." in most cases, so I think it is actually very common to > > have more than one level on the same DNS. > > Would you? I'd expect 'www' there to be in 'something', and 'something' > to be in a TLD (assuming context of a 3-label domain, not counting root) > > So for www to be in the same as something would mean it'd be in the TLD...
I think Bob means that www.something is not a zone cut. If it is a zone cut then the authoritative RRs for www.something can be on different name servers to something, e.g. . NS a.root-servers.net at. NS d.ns.at. dotat.at. NS black.dotat.at. www.dotat.at. NS lb.dotat.at www.dotat.at. SOA lb.dotat.at. (...) www.dotat.at. AAAA 2001:... So if you use an NS query to probe zone cuts, a straightforward implementation of query minimization requires four queries for a three label name (if the resolver has a primed but empty cache). If you use A queries you save a lookup in the common case where there isn't a zone cut at the leaf. Tony. -- f.anthony.n.finch <d...@dotat.at> http://dotat.at/ Dover, Wight, Portland, Plymouth: South 5 or 6, veering southwest 6 to gale 8, becoming cyclonic 4 or 5 later. Moderate or rough, occasionally very rough in Portland and Plymouth. Rain. Good, occasionally poor. _______________________________________________ DNSOP mailing list DNSOP@ietf.org https://www.ietf.org/mailman/listinfo/dnsop
