单项选择题 Whyisadatasourcerequired？（）

单项选择题 You have an Active Directory directory service forest with a forest root domain. The root domain has  two child domains named na.corp.contoso.com and asia.prod.contoso.com. You have an Active Directory  site for each domain. All sites are connected through the DEFAULTIPSITELINK site link. You need to  minimize the time that is required to authenticate users when they access resources in the other domain.   What should you do？（）

单项选择题 You are the network administrator for your company. The network consists of a single Active   Directory forest. The forest consists of 19 Active Directory domains. Fifteen of the domains contain  Windows Server 2003 domain controllers. The functional level of all the domains is Windows 2000 native.  The network also consists of a single Microsoft Exchange 2000 Server organization. You need to create  groups that can be used only to send e-mail messages to user accounts throughout the company. You  want to achieve this goal by using the minimum amount of replication traffic and minimizing the size of the  Active Directory database. You need to create a plan for creating e-mail groups for your company.  What should you do？（）