recursive clients ? / quota

Hi,

As you know when the limit of 1000 (by default, or whatever you
specify in named.conf) concurrent recursive clients is reached, you
get the following messages in the log:

Jun 30 08:53:11 xxxx named[5961]: client: warning: client
10.1.2.3#4015: no more recursive clients: quota reached

I was wondering what is really seen as a "recursive client" by BIND:

a) any queries as long as the "recursive" flag is set ? (even if it's
a query for a hostname the server is authoritative for...? or in the
cache?)

b) only recursive queries for which the server *has to* do the
recursive job ?

c) anything else ?

I am somehow confused that I have to set the value to 6000 to
completly get rid of the "no more rec client quota reached"
messages... even though the query rate is about 200-300 queries/sec
and most of them are legitimate and internal ones (internal hostname)

thanks
YMJ