> On Aug 25, 2018, at 2:53 PM, Paul Vixie <vi...@fsi.io> wrote:
>
> On Saturday, August 25, 2018 6:11:48 PM UTC Tom Pusateri wrote:
>> ...
>>
>> In most cases, having the primary remember the lease lifetime should be
>> enough. But if the outage is longer than the lease lifetime, it would
>> better if the secondary would also have that information.
>
> you seem to be proposing that the "secondary" servers, by which i mean those
> not the primary master, alter the zone contents in a way that's visible to
> query initiators, independently. if so, i oppose this, in the form proposed.
>
> to have more than one source of DNS truth requires "multi-master", so that
> zone identity can be partitioned and healed, following partitions and
> healings
> of the connectivity of each responder and its cloud of reachable clients. one
> of the hard problems here is split horizon. another is incompatible deltas at
> heal time. the database world has grappled with this topic, having varying
> degrees of success, for as long as there have been computer networks.
>
> i would like to see DNS add "multi-master". several proprietary vendor
> extensions do various parts of this -- though none of them that i know of can
> handle split horizon or incompatible deltas. and tellingly, none has been
> opened to the community in the form of a standardization effort.
>
> if on the other hand you only intend to carry the timeout information as zone
> data transferred in AXFR/IXFR in case a sysop decides that the primary master
> will be offline indefinitely and wants to manually promote one of the
> "secondary" servers to the role of primary master, then i have no objection.
> that's why the TUU and TUD RR's of my 1996 "defupd" proposal are in-zone data
> rather than stored in some ancillary location reachable only by the primary
> master.
>
> can you verify that you do not intend secondary servers to automatically
> expire records, independent of hearing IXFR/AXFR updates from the primary
> master, after the primary master applies its own copy of your TIMEOUT RR's?
>
> --
> Vixie
>
I agree that the secondary servers should not expire records. In the case of
promotion, I also agree that this sounds like a good strategy.
Thanks for pointing out this distinction.
Tom
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