Using the /etc/passwd file and network environments

In a traditional networked environment, a user must have had an account on each system to gain access to that system.

That typically meant that the user would have an entry in each of the /etc/passwd files on each system. However, in a distributed environment, there is no easy way to ensure that every system had the same /etc/passwd file. To solve this problem, several methods make the information in the /etc/passwd file available over the network, including Network Information System (NIS) and NIS+.