Thanks for the quick response Helen. We are planing on using the same external domain name (http:/mail.ourcompany.com/..service..) and public IP for all three services if possible. Thus, It sounds like a single domain certificate will work.
I have another question. I've enable SSL offloading on the CAS/Hub servers using the registry key in the following article ( http://technet.microsoft.com/en-us/library/bb885060%28EXCHG.80%29.aspx ) and disabled the SSL required check box on the IIS7 virtual website and directories . However when I enter the HTTP version of the owa url (http://CASserver/owa) it still automatically redirects to a SSL secure login page (https://CASserver/owa/auth/logon.aspx?replaceCurrent=1&url=https%3a%2f%2fCASserver%2fowa%2f. Is this going to be an issue for the F5?
Nimbostratus