Because even if you add TYPE, you have multiple PTR records (instance names) with the same owner name, class, and type that can timeout differently.
Tom > On Aug 26, 2018, at 11:20 PM, Ted Lemon <mel...@fugue.com> wrote: > > If we do that, why do we need a hash at all? > > On Sun, Aug 26, 2018 at 10:51 PM Mark Andrews <ma...@isc.org > <mailto:ma...@isc.org>> wrote: > I would add a covered type field to TIMEOUT (c.f. RRSIG). I also wouldn’t > have more than > a single timeout per record. I’m tempted to say a single hash as well. If > there is multiple > timeouts per record then the blocks need to be sorted in timeout order. > > Covered is there to reduce the number of RR’s that need to be hashed to > remove a record. > It will also reduce the size of IXFR’s as you don’t need to re-construct a > new TIMEOUT > record that covers every timeout at a name on each change. > > For all records at a name is often more expensive that for all records of > type covered. > Name servers are optimised for looking up <name,type,class> tuples rather > than <name,class> > tuples. > > Sorting of timeout blocks is so that you can look at the first timeout when > working out > which TIMEOUT needs to be processed first in a zone. > > -- > Mark Andrews, ISC > 1 Seymour St., Dundas Valley, NSW 2117, Australia > <https://maps.google.com/?q=1+Seymour+St.,+Dundas+Valley,+NSW+2117,+Australia&entry=gmail&source=g> > PHONE: +61 2 9871 4742 INTERNET: ma...@isc.org > <mailto:ma...@isc.org> >
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