Private IP Addresses 

If you are setting up a private network that is not going to be connected to the Internet, the following blocks of IP addresses are reserved for private networks according to RFC1597. The Internet Assigned Numbers Authority (IANA) has reserved these blocks of IPs for private networks: 

10.0.0.0 - 10.255.255.255
172.16.0.0 - 172.31.255.255
192.168.0.0 - 192.168.255.255