单项选择题 You create 200 new user accounts. The users are located in six different sites. New users report  that they receive the following error message when they try to log on： "The username or  password is incorrect."     You confirm that the user accounts exist and are enabled. You also confirm that the user name  and password information supplied are correct.     You need to identify the cause of the failure. You also need to ensure that the new users are able  to log on.     Which utility should you run（）

单项选择题 You need to identify all failed logon attempts on the domain controllers.     What should you do（）

单项选择题 A domain controller named DC12 runs critical services. Restructuring of the organizational unit  hierarchy for the domain has been completed and unnecessary objects have been deleted.     You need to perform an offline defragmentation of the Active Directory database on DC12.  You  also need to ensure that the critical services remain online.     What should you do（）