DNS

DNS is the naming service provided by the Internet for TCP/IP networks. It was developed so that machines on the network could be identified with common names instead of Internet addresses. DNS performs naming between hosts within your local administrative domain and across domain boundaries.

The collection of networked machines that use DNS are referred to as the DNS namespace. The DNS namespace can be divided into a hierarchy of domains. A DNS domain is a group of machines. Each domain is supported by two or more name servers, a principal server and one or more secondary servers. Each server implements DNS by running a daemon called in.named. On the client's side, DNS is implemented through the "resolver." The resolver's function is to resolve users' queries. It queries a name server, which then returns either the requested information or a referral to another server.

/etc Files

The original host-based UNIX naming system was developed for standalone UNIX machines and then adapted for network use. Many old UNIX operating systems and machines still use this system, but it is not well suited for large complex networks.

NIS

The Network Information Service (NIS) was developed independently of DNS and has a slightly different focus. Whereas DNS focuses on making communication simpler by using machine names instead of numerical IP addresses, NIS focuses on making network administration more manageable by providing centralized control over a variety of network information. NIS stores information about machine names and addresses, users, the network itself, and network services. 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 replace UNIX /etc files, as well as other configuration files, so they store much more than names and addresses. As a result, the NIS namespace has a large set of maps. See "Working With NIS Maps" for more information.

NIS uses a client-server arrangement similar to DNS. Replicated NIS servers provide services to NIS clients. The principal servers are called master servers, and for reliability, they have backup, or slave servers. Both master and slave servers use the NIS information retrieval software and both store NIS maps. For more information on NIS Architecture and NIS Administration, see Chapter 8, Setting Up and Configuring NIS Service and Chapter 9, Administering NIS (Tasks).

NIS+

The Network Information Service Plus (NIS+) is similar to NIS but with many more features. NIS+ is not an extension of NIS. It is a different software program.

The NIS+ naming service is designed to conform to the shape of the organization that installs it for almost any network configuration. Unlike NIS, the NIS+ namespace is dynamic because updates can occur and be put into 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 central locations where all machines on a network can have access to it. This configuration of network information is referred to as the NIS+ namespace.

The NIS+ namespace is hierarchical and is similar in structure to the UNIX directory file system. The hierarchical structure allows an NIS+ namespace to be configured to conform to the logical hierarchy of an organization. The namespace's layout of information is unrelated to its physical arrangement. Thus, an NIS+ namespace can be divided into multiple domains that can be administered autonomously. Clients might have access to information in other domains in addition to their own if they have the appropriate permissions.

NIS+ uses a client-server model to store and have access to the information contained in an NIS+ namespace. Each domain is supported by a set of servers. The principal server is called the primary server and the backup servers are called secondary servers. The network information is stored in 16 standard NIS+ tables in an internal NIS+ database. Both primary and secondary servers run NIS+ server software and both maintain copies of NIS+ tables. Changes made to the NIS+ data on the master server are incrementally propagated automatically to the secondary servers.

NIS+ includes a sophisticated security system to protect the structure of the namespace and its information. It uses authentication and authorization to verify whether a client's request for information should be fulfilled. Authentication determines whether the information requester is a valid user on the network. Authorization determines whether a particular user is allowed to have or modify the information requested. See System Administration Guide: Naming and Directory Services (FNS and NIS+) for a more detailed description of NIS+ security and administering it.

FNS

See System Administration Guide: Naming and Directory Services (FNS and NIS+) for information about FNS.

LDAP Naming Services

Solaris 9 supports LDAP (Lightweight Directory Access Protocol) in conjunction with the iPlanet™ Directory Server 5.1, as well as other LDAP Directory Servers.

See Chapter 12, Introduction to the LDAP Naming Service (Overview/Reference) for more information.

Naming Services: A Quick Comparison

	DNS	NIS	NIS+	FNS	LDAP
NAMESPACE	Hierarchical	Flat	Hierarchical	Hierarchical	Hierarchical
DATA STORAGE	Files/ resource records	2 column maps	Multi-columned tables	Maps	Directories [varied]
SERVER NAMES	Master/slave	Master/slave	Root master/non-root master primary/secondary cache/stub	N/A	Master/replica
SECURITY	SSL	None (root or nothing)	DES Authentication	None (root or nothing)	SSL
TRANSPORT	TCP/IP	LAN	LAN	LAN	TCP/IP
SCALE	Global	LAN	LAN	Global (w/ DNS)/LAN	Global