The /etc/networks file lists the names and addresses of your own, and other, networks. It is used by the route command, and allows you to specify a network by name, should you so desire.
Every network you wish to add a route to using the route command (generally called from rc.inet1---see above) must have an entry in /etc/networks.
As an example,
default 0.0.0.0 # default route - mandatory
loopnet 127.0.0.0 # loopback network - mandatory
mynet 220.127.116.11 # Modify for your own network address