Direct Access on Windows 2012 R2: Manage Out with a Hardware Load Balancer
A lot has been written regarding Manage Out for Direct Access (DA), but for those who may not be familiar with it, it is the mechanism within Direct Access that allows corporate endpoints to initiate...
Using this Manage Out method you don't have a fault tolerant solution for Windows 7 DA Clients.
"Step 1. Identify the IP-HTTPS IPv6 prefix for each DA server."
DA Servers will only have a unique IP-HTTPS (or Teredo) prefix if they are in separate DA Entry Points. If they are in separate DA Entry Points Windows 7 DA Clients won't failover between them.