Multisite scenarios are not always mutually exclusive, but in essence, they might include:
A single server in each site, with users assigned to a specific site
A single server in each site, with the user's computer detecting the fastest or closest entry point
A single server in each site, with global load balancing directing the traffic
A single server or an array at a main site, with other sites being on stand-by in case of disaster recovery
A scenario involving backward compatibility for Windows 7 clients
A variation, which could apply to any of the previous scenarios, is one where one or more of the sites have a load-balanced array of servers instead of a single server.
The primary difference between all of the above is how traffic is directed, based on the options we listed earlier. A URA entry point is associated with the active directory site in which it is placed, and clients which connect to that entry point are considered to be connected to that site. You don't have...