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AD is at 2003 functional level, some of our DC's are running Windows Server 2003, some are 2008, some are 2008 R2.

When using the following query:


I do not expect to see any result where the objectCategory attribute is equal to 'CN=Person,CN=Schema,CN=Configuration,DC=Contoso'

I expect only objects where the objectCategory attribute is equal to 'CN=User,CN=Schema,CN=Configuration,DC=Contoso'

However, the query does indeed return all objects with the objectCategory attribute equal to 'CN=Person,CN=Schema,CN=Configuration,DC=Contoso'

My question then is this: Why do I see the search results that I do? Does AD actively translate queries that include (objectCategory=user) to (objectCategory=Person)? I have looked at the schema definitions for both the Person and the User class, but I cannot see any reason for the query results as I am experiencing them. I know that the User class is a subclass of the organizationalPerson class, which is a subclass of Person, but I can't see an attribute value that would explain this translation.

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Can you clarify what objects you're expecting to see, and what you are seeing instead? Having that objectCategory is not unexpected for a user account object. – Shane Madden Mar 30 '12 at 16:38
up vote 0 down vote accepted

The reason you get the person objects is because there us no such category as User. User is a class. By strict definition Objectcategory takes a DN attribute. In order to avoid forcing coders to look up the schema DN, the query engine in AD allows you to provide a class and provides the defaultObjectCategory as the expansion. So if you were too look up the schema of User you get this as the defaultobjectcategory:


The proper expression to search for users is: "(&(objectClass=user)(objectCategory=person))".

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Perfect explanation! Thanks much, that explains away all my confusion on this issue. – Joseph Alcorn Apr 2 '12 at 20:51

User inherits from Person. In other words, users are Persons. The opposite is not true.

So if you search for user, you can also see persons.

From Technet:

enter image description here

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I was also hoping that by poinintg out the documentation you might read through it to discover the issue in your answer. The OP query is for a CATEGORY not a CLASS. – Jim B Mar 30 '12 at 19:40

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