Finding your base DN in Active Directory. I was trying to do an LDAP query against Active Directory and I was unable to get the query to work. A good tool to use to troubleshoot this is ldp.exe. It is installed by default on Windows Server 2008, but I believe its on the Windows Server 2003 disc, just not installed by default. A typical base DN is DC=microsoft, DC=com. I was using exactly the same logic and it still wasn't working.