You might need to use the scroll bar to view the entire contents of the panes in the work area. You can use the splitter bars to resize the panes. You have an Exchange Server 2010 Service Pack 1 (SP1) organization named contoso.com. A partner company named Fabrikam, Inc., has an Exchange Server 2010 (SP1) organization named fabrikam.com. All client computers in contoso.com and fabrikam.com run Microsoft Outlook 2010. You need to ensure that users in fabrikam.com can view the availability information of users in contoso.com.
What should you do?
A.
Create a forest trust from contoso.com to fabrikam.com. Create a forest trust from fabrikam.com to contoso.com.
B.
From contoso.com, create a federated trust. From fabrikam.com, create a federated trust.
C.
From contoso.com, create an organization relationship. From fabrikam.com, create an organization relationship.
D.
From contoso.com, modify the authentication settings of the EWS virtual directory. From fabrikam.com, modify the authentication settings of the EWS virtual directory.
Answer is “B”.
http://technet.microsoft.com/en-us/library/hh310374(v=exchg.141).aspx