> On Tue, Apr 01, 2008 at 06:34:38AM +1100, Mark Andrews wrote: > > > > Multiple PTR records do not scale. > > what does that mean Mark? > > why does "Multiple A records" scale and not others? > is this a DNS protocol issue or an implementation artifact?
Multiple PTR records scale worse than multiple A records. You get ~4000 A records in 64K. You get ~2000 AAAA records in 64K. > > Today we have reverse lookups that fail because people > > followed this path and exceeded the 64K DNS message size > > of TCP. > > and the same failure would be true for multiple instances > of any RR type. Yes. It's just very very rare for there to be enough of the other types to cause a problem. It's not uncommon for there to be too many PTR records to cause a problem especially when you start advocating that each address records needs a corresponding PTR record. The only reason we don't see more problems is that people have been saying that it is a waste of time to have multiple PTR records. > > When people have a 100 thousand virtual domains on a > > box you just can't have PTR records for all of them. > > and apparently you can't have A records for them either. > > > > > Mark > > so the actual spec limit is any mixture of RR types that > will fit into a 64k DNS message on TCP. Right? > > --bill > _______________________________________________ > DNSOP mailing list > DNSOP@ietf.org > https://www.ietf.org/mailman/listinfo/dnsop -- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: [EMAIL PROTECTED] _______________________________________________ DNSOP mailing list DNSOP@ietf.org https://www.ietf.org/mailman/listinfo/dnsop