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

Description of the /etc Files Naming ServiceThe original host-based UNIX naming system was developed for standalone UNIXmachines and then adapted for network use. Many old UNIX operating systems andmachines still use this system, but the system is not well suited for large complexnetworks.Description of the NIS Naming ServiceThe Network Information Service (NIS) was developed independently of DNS. DNSmakes communication simpler by using machine names instead of numerical IPaddresses. NIS focuses on making network administration more manageable byproviding centralized control over a variety of network information. NIS storesinformation about the network, machine names and addresses, users, and networkservices. This collection of network information is referred to as the NIS namespace.NIS namespace information is stored in NIS maps. NIS maps were designed to replaceUNIX /etc files, as well as other configuration files. NIS maps store much more thannames and addresses. As a result, the NIS namespace has a large set of maps. See“Working With NIS Maps” on page 97 for more information.NIS uses a client-server arrangement which is similar to DNS. Replicated NIS serversprovide services to NIS clients. The principal servers are called master servers, and forreliability, the servers have backup, or slave servers. Both master and slave servers usethe NIS retrieval software and both store NIS maps. For more information on NISArchitecture and NIS Administration, see Chapter 5 and Chapter 6.Description of the NIS+ Naming ServiceThe Network Information Service Plus (NIS+) is similar to NIS but with more features.However, NIS+ is not an extension of NIS.The NIS+ naming service is designed to conform to the shape of the organization.Unlike NIS, the NIS+ namespace is dynamic because updates can occur and be putinto effect at any time by any authorized user.NIS+ enables you to store information about machine addresses, security information,mail information, Ethernet interfaces, and network services in one central location.This configuration of network information is referred to as the NIS+ namespace.The NIS+ namespace is hierarchical. The NIS+ namespace is similar in structure to theUNIX directory file system. The hierarchical structure allows an NIS+ namespace to beconfigured to conform to the logical hierarchy of an organization. The namespace’slayout of information is unrelated to its physical arrangement. Thus, an NIS+namespace can be divided into multiple domains that can be administeredautonomously. Clients might have access to information in domains other than theirown if the clients have the appropriate permissions.28 System Administration Guide: Naming and Directory Services (DNS, NIS, and LDAP) • January 2005