Your company has a main office and a branch office. The offices connect by using WAN links. The network consists of a single Active Directory domain. An Active Directory site exists for each office. Servers in both offices run Windows Server 2008 R2 Enterprise. You plan to deploy a failover cluster solution to service users in both offices.

You need to plan a failover cluster to meet the following requirements:

Maintain the availability of services if a single server fails
Minimize the number of servers required

What should you include in your plan?

A.
Deploy a failover cluster that contains one node in each office.

B.
Deploy a failover cluster that contains two nodes in each office.

C.
In the main office, deploy a failover cluster that contains one node. In the branch office, deploy a failover cluster that contains one node.

D.
In the main office, deploy a failover cluster that contains two nodes. In the branch office, deploy a failover cluster that contains two nodes.

Explanation:
MCITP Self-Paced Training Kit Exam 70-646 Windows Server Administration:

Failover Clustering Failover clustering is a technology that allows another server to continue to service client requests in the event that the original server fails. Clustering is covered in more detail in Chapter 11, Clustering and High Availability. You deploy failover clustering on mission-critical servers to ensure that important resources are available even if a server hosting those resources fails.

Failover clustering The Failover Clustering feature enables multiple servers to work together to increase the availability of services and applications. If one of the clustered servers (or nodes) fails, another node provides the required service through failover and is available in Windows Server 2008 Enterprise and Datacenter editions and is not available in Windows Server 2008 Standard or Web editions.

Failover clustering – Formerly known as server clustering, Failover Clustering creates a logical grouping of servers, also known as nodes, that can service requests for applications with shared data stores.