IPv4 Addresses and Subnets

An IP address is a unique 32-bit number assigned to a specific network node. Some IP addresses are more or less permanent, such as those assigned to vital servers; others change as required, such as those used by desktop clients. Individual machines on a shared network use IP addresses from a range of addresses assigned to that network.

Rather than expressing that 32-bit address as a single number, an IP address is divided into four 8-bit numbers, usually expressed as decimals. While 192.0.2.1 and 11000000.00000000.00000010.00000001 represent the same address, the first option is easier for our feeble little brains to grasp.

Internet service providers (ISPs) issue IP addresses in blocks. These blocks are the smallest ...

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