If you use Network Policy Server (NPS) as a RADIUS server, RADIUS proxy server, or Network Access Protection (NAP) health policy server, you can find the following comprehensive technical references available for download in Word format from the Microsoft Download Center:
Network Policy Server (NPS) Technical Reference at http://www.microsoft.com/en-us/download/details.aspx?id=1898
Network Policy Server (NPS) Operations Guide at http://www.microsoft.com/en-us/download/details.aspx?id=16417
Thanks -
James McIllece