HOTSPOT
Your network contains an Active Directory domain named contoso.com. The domain
contains two Active
Directory sites named Site1 and Site2.
You need to configure the replication between the sites to occur by using change
notification.
Which attribute should you modify?
Answer: 
Explanation:
http://blogs.technet.com/b/qzaidi/archive/2010/09/23/enable-change-notifications-betweensites-how-andwhy.aspx
http://blogs.msdn.com/b/canberrapfe/archive/2012/03/26/active-directory-replication-changenotificationampyou.aspx
I agree