Your network contains an Active Directory domain named contoso.com. The domain contains a
server named Server1 that runs Windows Server 2012 R2. Server1 has the Network Policy Server
role service installed.
You plan to configure Server1 as a Network Access Protection (NAP) health policy server for VPN
enforcement by using the Configure NAPwizard.
You need to ensure that you can configure the VPN enforcement method on Server1 successfully.
What should you install on Server1 before you run the Configure NAP wizard?

A.
A computer certificate

B.
A system health validator (SHV)

C.
The Remote Access server role

D.
The Host Credential Authorization Protocol (HCAP)

Explanation:
http://technet.microsoft.com/fr-fr/library/dd314165%28v=ws.10%29.aspx