in /etc/network/interfaces allows computers on other subnets to ping / SSH this machine with a static IP but removing that line causes it to fail unless you're on the same subnet.
The "network" property is supposed to be optional (IP, netmask and gateway should be enough and is on other OS') so why did Ubuntu require it?
network network_address Network address (dotted quad) required for 2.0.x kernels
In CentOS it's actually deprecated:
NETWORK=<address>, where <address> is the network address. This directive is deprecated.
I've Googled and they should all be automatically calculated.
Thank you for your time,