In Chapter 1, we discussed the hardware requirements for installing UAG. The same requirements stand for DA as well, but with a vengeance. DA is based on IPSec tunnels, and every packet that goes to and from each client has to be encrypted or decrypted. In addition to that, some clients will also require SSL encryption on top of that. All this is very CPU intensive work, so if you thought you can just grab some old machine and milk it to the bone, think again.
As always with regards to performance, it's not easy knowing for sure at what point the server will start to choke. Microsoft's official performance information suggests that a server with 2 quad-core Xeon processors running at 2.26 GHz, and with 16 GB of memory can sustain approximately 2300 users, each having a data transfer rate of 0.1 Megabit per second (MBPS). That does not mean that if you get this exact hardware configuration you can count on that number of users to be serviceable, because certain things...