A hash is still better than copying the RDATA to the end of the timeout record and avoids protocol RR size limit issues.
You still have to handle multiple TIMEOUT RRs at the same name to cope with a TIMEOUT records that would exceed 64K, the limit of what can passed in a single RR in a AXFR. As these are never returned in a answer you don’t have to cope with the RRset exceeding 64k at the protocol level but a implementation might. e.g. 4000 A records at a single name (~64k RRset) with individual timeouts would have a TIMEOUT RRset much greater than 64k. Mark > On 27 Aug 2018, at 1:20 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> 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 > PHONE: +61 2 9871 4742 INTERNET: ma...@isc.org > -- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: ma...@isc.org _______________________________________________ DNSOP mailing list DNSOP@ietf.org https://www.ietf.org/mailman/listinfo/dnsop
