Naming and Directory Services (DNS, NIS, and LDAP)

A network information service stores network information on a server, which can bequeried by any machine.The machines are known as clients of the server. The following figure illustrates theclient-server arrangement. Whenever information about the network changes, insteadof updating each client’s local file, an administrator updates only the informationstored by the network information service. Doing so reduces errors, inconsistenciesbetween clients, and the sheer size of the task.forest/etc/hosts10.0.3.1 pine10.0.3.2 elm10.0.3.3 oakServer(stores information)Information(stored on server)pineelmoakWorkstations(request information)This arrangement, of a server providing centralized services to clients across anetwork, is known as client-server computing.Although the main purpose of a network information service is to centralizeinformation, the network information service can also simplify network names. Forexample, assume your company has set up a network which is connected to theInternet. The Internet has assigned your network the network number 192.168.0.0and the domain name doc.com. Your company has two divisions, Sales andManufacturing (Manf), so its network is divided into a main net and one subnet foreach division. Each net has its own address.Chapter 1 • Naming and Directory Services (Overview) 23