cas server for second webmail URL

Hi ,

In Exchange 2010 ,I have a plan to implement additonal cas sever for secondary webmail url (webmail2) for OWA access while primary URL (webmail1) not reachable.Can we  use this link (webmail2) for  secondary outlook anywhere URL when primary outlook anywhere url is not reachable?

Do i move RPCclientaccessserver to secondary cas server  when  both cas server in the same AD site?