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3. IP Classes

An IP address contains two pieces of information:

  • The address of the network, to allow one network to be told apart from all the others. This is needed so that messages can be sent between different networks.
  • The address of the node within the network, also known as the "subnet address" or "node address". This information is needed so that messages can be sent to a specific computer within a network.

But IP addresses are only 32 bits long. So how many of those bits should be set aside for the network address, and how many for the node address?

If you have a network with millions of nodes, you need a lot of space for the node address. But if you have millions of small networks, you need a lot of space for the network address. You don't have enough room for both within a 32-bit address system.

The organisation responsible for handing out IP addresses, ICANN, solved the issue by setting up a class system for networks.

These classes will be described on the following pages.


Challenge see if you can find out one extra fact on this topic that we haven't already told you

Click on this link: What is an IP Class