An IP address is assigned to every computer (and other devices such as switches and routers) on a network. It allows the network to identify each device.

An IP address can be private (when used on a LAN) or public (when used on the Internet).

Dynamic IP address - On the Internet, your ISP may have a number of addresses which are issued as each computer logs on. The IP address of the computer will stay the same until the computer disconnects from the Internet.

Fixed IP address - A computer always has the same IP address when connected to the Internet.

IP stands for
Internet Protocol

Eg 10101100 11001100 01000111 00010001

...which for simplicity is usually split into four 8-bit numbers and converted to decimal...

172.204.70.17

 If the IP address starts with 0 - the network is Class A
(128 networks - each with 16,777,214 hosts)

 If the IP address starts with 10 - the network is Class B
(16384 networks - each with 65534 hosts)

 If the IP address starts with 110 - the network is Class C
(2,097,152 networks - each with 254 hosts)

Some ranges are reserved for private networks. You will normally find a home network uses IP addresses in the range 192.168.0.0 to 192.168.255.255

The IANA (Internet Assigned Numbers Authority) oversees global IP address allocation.

Due to the expansion of the Internet a new 128-bit system (IPv6) is being introduced.

Run the program cmd to open the MS-DOS window.

Type ipconfig and press enter.

You should see your IP address.

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