TestKing.com has employed you as their Exchange Administrator. The TestKing.com network contains an Exchange Server 2010 Organization. The Exchange organization contains multiple Hub TransportServers. On of the Hub Transport servers named TESTKING-EX01 is used by a line of business application that retries e-mail messages. The application is configured to only send e-mail messages to a single SMTPserver. You receive an instruction from the CIO to ensure that the application is able to retry e-mailmessages of TESTKING-EX01 tabs. What should you do？（）

A. You should consider having failover clustering installed and configuring on the Hub Transport servers.
B. You should consider having Windows network load balancing implementing on the Hub Transport servers.
C. You should consider having log transactions implemented.
D. You should consider having multiple MX records created for the Hub Transport servers in the internal DNS zone.