You have an Exchange Server 2010 organization. 
You need to recommend a client access solution that meets the following requirements：
.Reduces the time required for users to reconnect to user mailboxes if a single Client Access server fails.Prevents users from being prompted for authentication if a single Client Access server fails
What should you recommend？（）

Your network contains an internal network and a perimeter network. The internal network contains a single Active Directory site. 
The perimeter network contains two Exchange Server 2010 Edge Transport servers. You plan to deploy an Exchange Server 2010 organization on the internal network. 
You need to plan the deployment of Hub Transport server roles to meet the following requirements：.If a single Hub Transport server fails， e-mail messages from the Internet must be delivered to the Mailboxservers.
.If a single Hub Transport server fails， users must be able to send e-mail messages to other users thathave mailboxes on the same Mailbox server. 
What should you include in the plan？（）