NFS, DNS, NIS and NIS+… that’s a lot of acronyms!

Network File System

NFS is Sun’s Networked File System, and by now, more or less, the de facto method of sharing file systems between computers.

Domain Name Service

DNS is the Domain Name Service, which is the way information about hostnames and addresses are shared across the Intenet.

Network Information (Name) Service

NIS stands for Network Information Name Service. It was original called Yellow Pages, which is why many of the commands for NIS start with yp (such as ypbind, ypcat, etc.) NIS was developed by Sun, and is, like NFS, more or less the default way of sharing system information between UNIX machines.

NIS+

NIS+ is Sun’s re-implementation of NIS. It attempts to address some of the problems with NIS, but the implementers of NIS+ have made a series of bad choices in the design of NIS+, so it has seen only limited usage compared to the other types of services you asked about.