You need to validate whether Active Directory successfully replicated between two domain  controllers.    
What should you do（）

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（）