[Serusers] Does lookup("location") queries the database or the memory?

Hello! I have found the db_mode option in the userloc module, which controls updates in the location table. But how are the lookups handled in ser? If a user location will be requested by lookup("location"), will this query the backend database or only the RAM. Is this lookup behaviour also configurable (how?)? I'm thinking about a configuration with 2 ser proxies and one database backend. If the lookup only queries the cached location table, I would have to froward the registrations between the two proxies via t_replicate. But wouldn't this cause both proxies to update the database resulting in two entries in the location table for each registration? regards, Klaus