When the enterprise's users and all this extra information are included, problems with scaling arise. Specific technical approaches vary. Besides distribution, replication is necessary. Until recently, for example, Banyan StreetTalk distributed but did not replicate item-level data. If a user's home server failed, he could not log in, even if there were other services on other servers with which he could work.
Replication removes the single point of failure problem from directory services.
In NetWare's case, some vendors have really used this, though they are typically only for additional system administrator functions. Maybe the new Novell Net2000 API marketing thrust will gain them market share. Next comes directory service for other network services or applications. More and more network applications are on their way every day. Each seems to arrive with its own internal directory service, one optimized for its needs but obviously containing similar content to NOS directories.