Unrouteable private ip address
There are three address ranges designated as private as per RFC 1918:
10.0.0.0…10.255.255.255(10/8) - (Class A network that start with10.)172.16.0.0…172.31.255.255(172.16/12) - (Class B networks that start with172.16.)192.168.0.0…192.168.255.255(192.168/16) - (Class C networks that start with192.168.)