If a network card is to be configured, you have to decide on the IP-address, FQDN and possible aliases for use in the /etc/hosts file. The syntax is:

<IP address> myhost.example.org aliases

Unless your computer is to be visible to the Internet (e.g. you have a registered domain and a valid block of assigned IP addresses - most of us don't have this)you should make sure that the IP-address is in the private network IP-address range. Valid ranges are:

     Class Networks
        A     10.0.0.0
        B     172.16.0.0 through 172.31.0.0
        C     192.168.0.0 through 192.168.255.0

A valid IP address could be 192.168.1.1. A valid FQDN for this IP could be www.linuxfromscratch.org (not recommended as this is a valid registered domain address and could cause your domain name server problems).

If you aren't going to use a network card, you still need to come up with a FQDN. This is necessary for certain programs to operate correctly.

If a network card is not going to be configured, create the /etc/hosts file by running:

cat > /etc/hosts << "EOF"
# Begin /etc/hosts (no network card version)

127.0.0.1 <value of HOSTNAME>.example.org <value of HOSTNAME> localhost

# End /etc/hosts (no network card version)
EOF

If a network card is to be configured, create the /etc/hosts file by running:

cat > /etc/hosts << "EOF"
# Begin /etc/hosts (network card version)

127.0.0.1 localhost
192.168.1.1 <value of HOSTNAME>.example.org <value of HOSTNAME>

# End /etc/hosts (network card version)
EOF

Of course, the 192.168.1.1 and <value of HOSTNAME>.example.org have to be changed to your liking (or requirements if assigned an IP-address by a network/system administrator and this machine is planned to be connected to an existing network).