Your company has an Exchange 2010 organization that contains multiple Hub Transport servers. You have a line-of-business application that relays e-mail messages by using a Hub Transport servernamed Hub1. 
The application only supports sending e-mail to a single SMTP server. 
You need to ensure that the application can relay e-mail messages if Hub1 fails. 
What should you do？（）

Your company has an Active Directory forest named contoso.com. 
You plan to deploy an Exchange Server 2010 organization that will contain two servers. 
Each server will have the Client Access server role， the Hub Transport server role， and the Mailbox serverrole installed. 
You plan to add both servers to a database availability group （DAG）. 
You need to recommend a high-availability solution for the Client Access server role. 
Your solution must ensure that users are not prompted to authenticate if a Client Access server becomesunavailable. 
What should you recommend？（）