"This document contains both the Design Guide and the Deployment Guide for DirectAccess in Windows Server 2008 R2. These guides help you to design and deploy DirectAccess servers, DirectAccess clients, and infrastructure servers on your intranet.
Use the Design Guide to answer the "What," "Why," and "When" questions a deployment design team might ask before deploying DirectAccess in a production environment.
Use the Deployment Guide to answer the "How" questions a deployment team might ask when implementing a DirectAccess design.."
These documents will get you off to a good start.
Check them out at:
Thomas W Shinder, M.D., MCSE
Sr. Consultant / Technical Writer