> 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
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--
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742 INTERNET: [EMAIL PROTECTED]
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