You are creating a plan to ensure that if an Internet link failure occurs at your primary datacenter, and you successfully move your mailboxes over to the DR site, that all users will be able to connect.
You want to do this with the least IT management tasks required. (Choose all that apply.)
A. Ensure that all ExternalURLs for all protocols are mail.contoso.com.
B. Ensure that OWA has its ExternalURL set to mail.contoso.com but that all other protocols have ExternalURL set to null.
C. Configure your internal DNS server to have an A record for each CAS server in both sites listed with their own IP address.
D. Configure your internal DNS server to have an A record for mail.contoso.com that has the IP address of your load balancer that load balances Exchange
Servers in the primary datacenter as the IP address of this A record.
E. Configure your external DNS server to have an A record for each CAS server in both sites listed with their own IP address.
F. Configure your external DNS server to have the externally NATed IP address of your load balancer that load balances Exchange Servers in the primary datacenter.
