You work as the exchange administrator at Testking.com. The TestKing.com network contains an ActiveDirectory forest. You are planning the deployment of two Edge Transport servers as well as two Hub Transport Servers.You decide to recommend changes to the organization in order to make sure that users are able to sende-mail messages to the Internet in the event of a transport server failing. What should you do？（）

A. You should recommend that the Edge Transport servers are configured as source servers for a Sendconnector.
B. You should recommend that shadow redundancy be configured for the Hub Transport servers.
C. You should recommend that one mal exchange （MX） record and one SRV record be created for every Edge Transport server in the internal DNS zone.
D. You should recommend that failover clustering be implemented on both Hub Transport servers.