Private IP Address
A private IP address identifies a device on a local network (LAN). It is similar to a public IPv4 address, which identifies a device connected to the Internet, but is limited to a predefined range of IPs.
Below are three common ranges of IP addresses reserved for private IPs:
- 10.0.0.0 – 10.255.255.255
- 172.16.0.0 – 172.31.255.255
- 192.168.0.0 – 192.168.255.255
10.0.0.1, for instance, cannot be used as a public IP address because it falls in the range of private IPs. Instead, 10.0.0.1 can only be assigned to a router, computer, or another device on a local network. Routers incrementally assign IP addresses to devices when they connect to the network, via DHCP. For example, a router may use the address 10.0.0.1 and assign 10.0.0.2 to the first device that connects to it. The following device will receive an address of 10.0.0.3, then 10.0.0.4, etc.
192.168.x.x vs 10.x.x.x
Most local networks use the 192.168.x.x range of private IPs. The second most popular range is 10.x.x.x, followed by 172.32.x.x. Generally, the router manufacturer determines the default range. For example, Linksys and Netgear routers typically use 192.168.0.1 or 192.168.1.1 for the router IP address, and therefore the IP ranges of 192.168.x.x. Apple routers (now discontinued) used the 10.0.0.x range. The 172.31.x.x range is the least common but may be used by large networks, such as university campuses and office buildings.
NOTE: Network address translation (NAT) translates the private IP address of each device on a network to the public IP address assigned by the ISP. Thanks to NAT, all devices connected to a router share the same public IP address.