LDAP searches with empty base-dn

Hello.I’ve got the following configuration: LDAP running with a secondary domino directory included via directory assistance. Using a LDAP browser I can see both users from my names.nsf and the secondary directory.

But when using ldapsearch.exe or the search functionality of the LDAP Browser and entering NO base-DN for the search, I only find people of my names.nsf.

Wenn entering “O=secondACME” as base-dn, i get search results from the secondary directory.

Can anyone explain this to me?