How Name Services Affect the hosts Database

The NIS, NIS+, and DNS name services (or LDAP as a name service) maintain host names and addresses on one or more servers. These servers maintain hosts databases that contain information for every host and router (if applicable) on the servers' network. Refer to System Administration Guide: Naming and Directory Services (DNS, NIS, and LDAP) and System Administration Guide: Naming and Directory Services (FNS and NIS+) for more information about these services.

When Local Files Provide Name Service

On a network that uses local files for name service, machines that run in local files mode consult their individual /etc/inet/hosts files for IPv4 addresses and host names of other machines on the network. Therefore, these machine's /etc/inet/hosts files must contain the following:

• Loopback address

• IPv4 address and host name of the local machine (primary network interface)

• IPv4 address and host name of additional network interfaces that are attached to this machine, if applicable

• IPv4 addresses and host names of all hosts on the local network

• IPv4 addresses and host names of any routers that this machine must know about, if applicable

• IPv4 address of any machine your machine wants to refer to by its host name

The figure below shows the /etc/inet/hosts file for machine tenere. This machine runs in local files mode. Notice that the file contains the IPv4 addresses and host names for every machine on the 192.9.200 network. The file also contains the IPv4 address and interface name timbuktu-201. This interface connects the 192.9.200 network to the 192.9.201 network.

A machine that is configured as a network client uses the local /etc/inet/hosts file for its loopback address and IPv4 address.

Figure 5–1 /etc/inet/hosts File for Machine Running in Local Files Mode