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127.0.0.1 localhost
127.0.1.1 optimus

#   The following   lines   are desirable   for IPv6    capable hosts

::1                 ip6-localhost   ip6-loopback

fe00::0 ip6-localnet

ff00::0 ip6-mcastprefix

ff02::1 ip6-allnodes

ff02::2 ip6-allrouters

ff02::3 ip6-allhosts

The first entry is for the loopback entry. The second is for the name of the
machine. If no naming service is in use on the network, the only host that
myhost recognizes by name is yourhost. (IP addresses on the network
can still be used.)

Service Settings in /etc/services

The /etc/services file maps port numbers to services. The first few
lines of the file (which can be more than 500 lines long in total) look similar
to this:

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Each line describes one service, and is of the form:

service-name port/protocol [aliases ...] [# comment]

tcpmux                  1/tcp                                                       #   TCP port    service multiplexer

tcpmux                  1/udp                                                       #   TCP port    service multiplexer

rje                             5/tcp                                                       #   Remote  Job Entry

rje                             5/udp                                                       #   Remote  Job Entry

echo                            7/tcp

echo                            7/udp

discard             9/tcp                       sink    null

discard             9/udp                       sink    null

systat                  11/tcp                  users

Typically, there are two entries for each service because most services can use
either TCP or UDP for their transmissions. Usually after /etc/services
is initially configured, you do not need to change it.

Using /etc/nsswitch.conf After Changing Naming

Services

The /etc/nsswitch.conf file was initially developed by Sun