You have an Exchange organization. The Exchange servers in the organization are
configured as shown in the following table:

You deploy a new Exchange Server 2010 Client Access server named Server4 and
successfully update the required DNS records for Server4.
You need to ensure that all users on Server3 can successfully access their mailboxes by
using Exchange ActiveSync.
What should you do?

A.
On Server1, set the authentication type for the Microsoft-Server-ActiveSync virtual
directory to Integrated Windows Authentication.

B.
On Server1, set the authentication type for the Microsoft-Server-ActiveSync virtual
directory to anonymous.

C.
From the Exchange Management Shell on Server4, run NewActiveSyncDeviceAccessRule -QueryString
* -Characteristic DeviceModel -AccessLevel Allow.

D.
From the Exchange Management Shell on Server3, run Set-ActiveSyncVirtualDirectory –
Identity”Server3\ Microsoft-Server-ActiveSync (default web site)” -Basicauthentication:$true.

Explanation:

http://blogs.technet.com/b/exchange/archive/2009/11/20/3408856.aspx