Too many SOA-Queries from Secondary

[Tom Schmitt]

Hi out there,

I have a primary and a secondary Bind, both BIND 9.3.1rc1. I expect the
secondary server to ask from time to time for the SOA of the domain
example.com.

When I have a look in the logfile of the primary I see this expected
request. But I don't see it one time: Everytime the secondary asks for the
SOA, he sends six (!) queries. 
My question is: Why does he do this an how can I change it?


More information on my configuration might help: