21. NIS and LDAP
NIS (Network Information Service) simplifies the maintenance of common administrative files by keeping them in a central database and having clients contact the database server to retrieve information from the database. Developed by Sun Microsystems, NIS is an example of the client/server paradigm.
Just as DNS addresses the problem of keeping multiple copies of /etc/hosts files up-to-date, NIS deals with the issue of keeping system-independent configuration files (such as /etc/passwd) current. Most networks today are heterogeneous (page