On a network using local files for name service, machines running in local files mode consult their individual /etc/inet/hosts files for IPv4 addresses and host names of other machines on the network. Therefore, their /etc/inet/hosts files must contain the:
Loopback address
IPv4 address and host name of the local machine (primary network interface)
IPv4 address and host name of additional network interfaces 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 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, a machine that 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. It also contains the IPv4 address and interface name timbuktu-201, which connects the 192.9.200 network to the 192.9.201 network.
A machine configured as a network client uses the local /etc/inet/hosts file for its loopback address and IPv4 address.