Friday, May 29, 2009

IP Adress Ranges

Most people are aware that IP addresses starting with 192.168 (192.168/16) belongs to a private network. Private means that the address range is reserved by IANA (Internet Assigned Numbers Authority) to be used for internal networks. But there are more private network address ranges then that. In fact the entire range of addresses starting with 10 (10/24). As does all addresses starting with 172.16 to 172.31 (172.16/12).

If you just have a small local network, the 192.168 range will do nicely as it will fit 65,536 (2^16) uniquely addressed devices.

Though you shouldn't assign the last 255 address to a device, in this case 192.168.255.255, since this is used as the broadcast address. It's called broadcast address since a message sent to that address is sent to all the addresses in the network.

Similarly you shouldn't assign the very first address either, in this case 192.168.0.0, since that is often reserved by network devices such as routers as a reference to the network.

If you have a bit more devices in your network, you can use the range 172.16 to 172.31 as that holds 1,048,576 (2^20) addresses.

An even bigger private network would use addresses starting with 10, as that would hold 16,777,216 (2^24) addresses.

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