Solaris Transition Guide

Chapter 13 Using Name Services

The network information service (NIS), which is part of the SunOS release 4 environment, is gradually being replaced with the network information service plus (NIS+). NIS+, introduced with the SunOS 5.0 system, is a completely redesigned name service that takes into account changes in customer client/server environments. DNS ( domain name system) is an existing, complementary name service used for intercompany Internet communication. This chapter discusses NIS+ and compares it to NIS and DNS.

For more information about planning an NIS+ upgrade and installing NIS+, see NIS+ Transition Guide and Solaris Naming Setup and Configuration Guide.

Note -

The system administration documentation set for the Solaris 7 operating environment emphasizes a system that is using NIS+.

Name Service Switch

The Solaris 7 operating environment uses standard naming interfaces (for example, gethostbyname) to support multiple naming services (such as NIS, NIS+, and DNS, among others), thereby allowing applications to access data transparently from different services. One instance of this is the Name Service Switch capability in the Solaris 7 operating environment, which allows applications to use a UNIX standard naming interface (for example, getxxbyyy interfaces). See the nsswitch.conf(4) man page for more information.


NIS+ is a name service built on top of the ONC transport-independent remote procedure call (TI-RPC) interface. NIS+ has significant advantages over NIS in the areas of security, performance, scalability, and administration.


DNS supports the model of a hierarchical name space with autonomously administered name servers. Although NIS+ uses a similar hierarchical naming model, it focuses on supporting changing system administration data and other requirements of enterprise networks.

DNS and NIS+, therefore, are complementary name services:

DNS and NIS+ Comparison

Table 13-1 shows the features and benefits of DNS compared to NIS+.

Table 13-1 DNS and NIS+ Features and Benefits Compared





Unrestricted access to data 

All operations can be authenticated 



Administrator designates access rights for objects and entries 

API and human interface  

Allows read-only access to name service 

Allows read-write access to name service. Provides: 

- Efficient support of changing network environment 

- API support of administrative operations 

- Support of administrative and other distributed applications 


By transfer of zone master files 

By incremental data transfer 

- Fast support of changing network environments 

- Stronger consistency 

Compatibility with NIS 

Not applicable 

Existing NIS applications can migrate smoothly 

Data support 

ASCII data only with packet size restriction 

Binary and ASCII data. Provides: 

- Support of variable information 

- Support of larger objects 

The main strength of DNS is in supporting hierarchical database partitions and replicas containing entries of relatively static information (such as host name and IP address). DNS enables you to access the Internet.

NIS+, in contrast, is a secure repository of changing administrative information (such as email aliases, Ethernet addresses, RPC program numbers) for enterprise networks.

NIS and NIS+ Comparison

Table 13-2 summarizes several major enhancements in NIS+ compared to NIS.

Table 13-2 NIS and NIS+ Features Compared




Name space 

Has a flat on-hierarchical organization; centralized flat file database for each independent network domain  

Has a hierarchical organization; partitioned into directories to support each network subset or autonomous domain 

Data Storage Scheme 

Multiple bicolumn "maps" (files) having key-value pairs 

Multicolumn database with multiple, searchable columns 

Resource Access Across Domains 

Not supported 

Permitted for authorized users 

Privileges for  


Updates require superuser privileges on master server 

Updates can be performed remotely by authorized users  

Update Process 

Updates require using make files on master servers 

Updates are performed easily through command-line interface 



Is administrator initiated and requires transfer of whole maps 

Automatic and high-performance updating via incremental transfer  


Database not secure 

Fine-grained access control to NIS+ directories, table column, and entries 

Commands and Functions Prefixes 

Prefixed by the letters yp, as in ypmatch(1) and ypcat(1)

Prefixed by the letters nis, as in nismatch(1) and nischown(1)

NIS+ includes features that enable NIS sites to migrate to the new name service in a smooth, phased manner. NIS sites that migrate to NIS+ will gain the following benefits:

Planning NIS+ Upgrade

NIS+ supports the following combinations of operating environments: