Standalone DFS structures can be created on any server running Windows 2000 with DFS installed (it is installed by default). With standalone DFS, Active Directory is not required. Creating a DFS structure begins with a server hosting the ‘root’ of DFS. This is the shared folder that will first be connected to by clients. With Standalone DFS, this root can only be hosted on a single server. As such, if this server fails, users will not be able to gain access to the DFS tree (of course, they will still be able to access resources that exist on other physical servers if they knew the location of those folders). Standalone DFS does not support having replicas of the root, although you can configure replicas of folders beneath the root. This would allow users to be load-balanced between folders that exist of different servers, but contain identical information. Note that in a standalone DFS setup, the replication of data between replicas does not happen automatically – you must somehow make replication happen between the replicas (using a tool such a robocopy, for instance).
Domain-based DFS takes advantage of Active Directory by storing DFS topology information in Active Directory. This type of DFS supports the ability to have root replicas, which provide both load-balancing and fault-tolerance. For example, if multiple root-replicas were created and a replica is taken offline, a user can still access the DFS structure, simply by being redirected to another replica. On top of this, replicas of shared folders can also be created, and replication can take place automatically using the file replication service (FRS) – up to 32 replicas are supported. In the case of domain-based DFS, the root points not to a server, but instead to the domain – an example of a DFS root might be \\win2000trainer.com\dfsroot. Using site information stored in Active Directory, a user attempting to access the DFS root would be redirected to the root replica in their own site, for example, instead of accessing the root from over the WAN. Note that in order to access domain-based DFS, a client running Windows 9x, or Windows NT 4 needs to have the Active Directory client software installed.