It does not necessarily list every server of a given type. Many name servers, etc, are run for specific departments or clusters of computers. Servers listed here are intended for general use. In many cases you should check with your departmental liaison to see whether your there is a server in or near your department. However these should be safe to use.
Information here is intended for technically knowledgable readers.
The campus divisions have instructions that are probably more appropriate for most users. Services are listed alphabetically. A number of departments provide anonymous FTP on the primary departmental systems. Thus this list is not going to be anywhere near complete. This is intended as an access point to several collections of primarily Unix-related items.