Your network contains a single Active Directory domain that has two sites named Site1 and Site2.  Site1 has two domain controllers named DC1 and DC2. Site2 has two domain controllers named  DC3 and DC4.  DC3 fails.  
You discover that replication no longer occurs between the sites. You verify the connectivity  between DC4 and the domain controllers in Site1.  On DC4， you run repadmin.exe /kcc.    
Replication between the sites continues to fail.  
You need to ensure that Active Directory data replicates between the sites.    
What should you do（）

Your network contains an Active Directory domain. The domain is configured as shown in the  following table：  
Active Directory site  Domain controllers  Main  DC1 and DC2  Branch1  DC3  Branch2  None    
Users in Branch2 sometimes authenticate to a domain controller in Branch1.  
You need to ensure that users in Branch2 only authenticate to the domain controllers in Main.    
What should you do（）