On Jun 11, 2015, at 5:54 PM, Tony Finch <d...@dotat.at> wrote: > I think the penultimate paragraph of section 2 is a bit confusing. I > suggest (starting with the existing text, for context)... > > To do such minimisation, the resolver needs to know the zone cut > [RFC2181]. Zone cuts do not necessarily exist at every label > boundary. If we take the name www.foo.bar.example, it is possible > that there is a zone cut between "foo" and "bar" but not between > "bar" and "example". So, assuming the resolver already knows the > name servers of .example, when it receives the query "What is the > AAAA record of www.foo.bar.example", > > (new text) > > it does not know how many labels it needs to append before it will find > the zone cut. If it uses QNAME minimization, it will guess there is a cut > between "bar" and "example" so it will query the .example name servers for > the NS records for bar.example. It will get a NODATA response, indicating > there is no cut at that point, so it has to to query the .example name > servers again with a longer name. > > Without QNAME minimization, it would send the .example nameservers a query > for www.foo.bar.example and immediately get a referral for > foo.bar.example, without the need for more queries to probe for the zone > cut. Section 6 discusses this performance discrepancy further. > > (end)
I like Tony's new text, and found it easier to follow that the current text. We sometimes forget that people have heard that every dot makes a new level in the DNS and so having a clear explanation of zone cuts as they affect minimization is useful for those who are not normal implementers. --Paul Hoffman _______________________________________________ DNSOP mailing list DNSOP@ietf.org https://www.ietf.org/mailman/listinfo/dnsop
