Re: [dhcwg] DDNS-DHCP [6]: Relationship between DNS TTL and DHCP lease length

> Still, when new records are created, you have to propagate the
> information outwards.  Rsync, AXFR and IXFR are all unsuitable for
> this in a frequently changing environment due to their associated
> overhead. ...

"sez you."  before it was called dnsext, this wg was called dnsind.  that
stood for Incrementalzonetransfer, Notificationofchanges, and Dynamicupdate;
these were the three features that the powers that were decided were needed
in order to support DHCP and IPv6, which were the New things in ~1994.

the architectural paradigm was to use Update to get things into the master,
Notify to make the slaves aware of these new changes without waiting for an
SOA timer to expire, and IXFR to get these changes distributed to the slaves
without having to transfer all the unchanged data as well.

interestingly, ohta-san preferred a different, masterless model, but he still
did IXFR when consensus went in favour of the i-n-d model.  also interesting
was microsoft, who went for a masterless model using non-DNS channels for
synchronization (but they never did implement healing after a partition event.)

now as to performance.  a company who was bundling BIND8 into a dhcp/dns
integration product stress tested the i-n-d model, and found all kinds of
early (pre-Y2K) data corruption bugs in our IXFR implementation.  their goal
was to be able to shoot thousands of DHCP-originated PTR updates per second
through BIND8 and have the slaves remain synchronized -- and it all works
fine.  therefore i dispute ("sez you") your assertion of "unsuitable".

various other commercial entities, mostly non-BIND based, have also reached
these transaction volumes, using the i-n-d model.  you may not think it's
pretty, but noone has yet found a real world workload that the model can't
address if you use the right hardware and software to support the load.

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