Looking to set up Direct Access (DA) and wondered what was required of your infrastructure?
List shamelessly stolen from Edge.technet.com
DirectAccess requirements include:
  • A DirectAccess server (a Windows Server 2008 R2 joined to an Active Directory® domain with DirectAccess Management Console feature added and cannot be behind a Network Address Translation, or NAT, device) with two network adapters: one connected to the Intranet, and the other to the internet with at least two consecutive public IPv4 addresses
  • All DirectAccess clients running Windows 7
  • At least one domain controller and Domain Name System (DNS) server running Windows Server 2008 SP2 or Windows Server 2008 R2
  • Public Key Infrastructure (PKI) for issuing computer certificates, smart card certificates, and, for Network Access Protection (NAP), health certificates
  • IPsec policies to specify protection for traffic
  • IPv6 transition technologies, i.e. ISATAP (RFC 4214), Teredo (RFC 4380), and 6to4 (RFC 3056), for DirectAccess server
  • Optionally, a non-Microsoft NAT-PT (RFC 2766) device to provide access to IPv4-only resources for DirectAccess clients