If you run a query against the Active Directory data of a specific container, the query returns only a subset of the items ...

If you run a query against the Active Directory data of a specific container, the query returns only a subset of the items that are displayed in the management list for this container. For example, if the maximum number of displayed items is set to 10,000 and you run a query against an organizational unit (OU) that contains 50,000 objects, the query returns only a subset of the 10,000 objects that are displayed in the management list for this OU.