IXFR - concept by serialnumbers of SOA-RR?

[Oliver Grether]

After studying the manuals and RFCs I have a question to the way,
IXFR-transfers
are requested. If I have read all the information correct, then IXFR is
also based
on the serialnumbers in the SOA-RRs. These serialnumbers have 10
numbers, by default
used as yyyymmdd##. By this there are a maximum of 100 changes per day.

Now my question is, if I would have configured a short refresh-time
using IXFR, how is
it handled, if I really have many nsupdates? Perhaps in big
conference-pools I think
there is no problem to have some hundred nsupdates per day. Do I have to
configure the
refresh-time in dependancy of the maximum daily possible changes of the
serialnumber in
the SOA-RRs? In general, is IXFR really only a way to reduce the
traffic, but not to 
speed up the notify-cycles?

The background of this questions is the following scenery:

I have about 1200 IP-Clients, including about 250 Voice-Over-IP-Clients
( VoIP ). If
there would cause a power-disconnect of the building for more than
perhaps half a day,
all the DHCP-leases would be expired. At power-reconnect all IP-Clients
would boot up
in a very short time, each producing a nsupdate. Because the
VoIP-Clients should work as
fast as possible, I would like to configure a short refresh-time, but
that would exceed
the daily possible changes.

Thanks in Advance.

Oliver Grether

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