A corporate environment includes Exchange Server 2010. The Exchange Server environment includes
two Hub Transport servers, two Client Access servers, and two Mailbox servers on the internal
network and two stand-alone Edge Transport servers in the perimeter network. The Mailbox servers
are in a database availability group (DAG). You are designing a solution to allow a third-party
application to send email messages to both internal users and external users.
You have the following requirements:
• Ensure that the third-party application can use domain-based NTLM authentication method for
outgoing messages.
• Ensure that if only one server has a hardware failure, all outgoing messages are accepted for
delivery.
• Minimize the cost of the solution.
You need to recommend a solution that meets the requirements. What should you recommend?

A.
Configure DNS round-robin rotation for SMTP connections to the Mailbox servers

B.
Deploy a hardware load balancer for SMTP connections to the Edge Transport servers

C.
Configure DNS round-robin rotation for SMTP connections to the Edge Transport servers

D.
Deploy a hardware load balancer for SMTP connections to the Hub Transport servers

Explanation: