AAF single server for multiple apps / databases

I just read through the multiple-database guide and think I roughly
understand the process of hashing the domain for purposes of keeping
unique indexes. My question though is that I want to be able to keep
separate indexes for separate apps under the control of a single ferret
DRB server hosted on a single physical “search” server.

When searching using AAF and this mutli-db system does it only return
results from the DB of the calling domain, or does it return results for
all indexes, but only writes to that domains index?

I’m hoping for a way on my search server to have a single AAF DRB server
running but each domain / application (who all share the same DB Schema,
so no worries there) only gets it’s specific search results.