notify timed out/exceeded

[Gamer]

Hi John,
i already found the hint "ndd -set /dev/udp udp_recv_hiwa" but it
didn't help.. But i changed some settings:

on the master NS:

options {
...
transfer-out 20;
}

on the slaves:

server 192.168.0.1 {
transfers 4;
}

Previously, I had transfer-out:40 and transfers:10 - maybe that was a
bit too much?! With the new settings no timeouts/exceeds occured in the
logs! But the question is:
How many slaves can be supported by a single Master Nameserver? Ok, it
depends on how many RR`s are dynamicly added to the Master Zonefiles
and hardware recources, I guess. But are there some known limits or
performance tests I can use to get some impressions?