Using the Name Service Switch

The name service switch is designed to simplify name service administration. Client machines and applications use this switch to select a name service. The switch mechanism is implemented using the /etc/nsswitch.conf file, which specifies the source(s) used to resolve references for each information type.

This section discusses only those elements that are needed to properly configure the name service switch for NIS operation. For a more detailed description of the nsswitch.conf file, see Chapter 2, The Name Service Switch.

An nsswitch.conf file is automatically loaded into every machine's /etc directory by the Solaris operating environment software, along with three alternate (template) versions:

• /etc/nsswitch.nisplus

• /etc/nsswitch.nis

• /etc/nsswitch.files

These alternate template files contain the default switch configurations used by the NIS+ service, NIS, and local files. (See "The nsswitch.conf Template Files".) No default file is provided for DNS, but you can edit any of these files to use DNS (see "DNS Forwarding for NIS Clients").

This switch functionality does not exist under SunOS 4.x. Thus, DNS forwarding for 4.x clients must be done on the NIS server. In this situation, if a 4.x client requests information for a host that is not listed in the NIS server's NIS map, the NIS server forwards the client's host request to a DNS server on the client's behalf.

When Solaris operating environment software is first installed on a machine, the installer selects the machine's default name service: NIS+, NIS, or local files. During installation, the corresponding template file is copied to /etc/nsswitch.conf. For a machine client using NIS, the installation process copies nsswitch.nis to nsswitch.conf. Unless you have an unusual NIS database setup, the default /etc/nsswitch.nis template file as copied to nsswitch.conf should be sufficient for NIS operation.

When changing a machine client from naming system (/etc, NIS or NIS+) to another, you copy the corresponding template file to nsswitch.conf. You can also change the sources of particular types of network information used by the client by editing the appropriate lines of the /etc/nsswitch.conf file. See Solaris Naming Setup and Configuration Guide, and Chapter 2, The Name Service Switch.

If the /etc/nsswitch.conf file is set to files and not nis for host information, and the server is not included in the /etc/hosts file, then the ypcat command generates the following error message: RPC failure: "RPC failure on yp operation"