What are Internet Addresses?

Absolutely every single interface or device in the internet must have a unique internet address.  These are probably more commonly known as an IP address.    The addresses consist of 32 bit numbers, these are arranged in specific structures and are not ordinary flat addresses that we are more used to.

There are five different classifications of internet addresses as follow – Class A, B, C , D and E all covering different ranges.   The 32 bit numbers are normally written as four decimal numbers which correspond to different bytes of the address.  The notation is well established now and is usually known as the dotted decimal notation or system.

You can easily differentiate between the different classes of IP addresses by looking at the first numbers.

  • Class A –  0-127
  • Class B – 128-191
  • Class C – 192-223
  • Class D – 224-239
  • Class E – 240-255

Remember these refer to the first number in the decimal notation, so for example the IP address would be classified as a Class C address.   Also worth remembering is the fact that many network devices are multi-homed and can contain several network interfaces which will have different IP addresses possibly in different classes.

There is an important point to remember about these internet address – because each one has to be unique there  must be one central authority for controlling them.   This authority is known as the Internet Network Information Centre otherwise known as the InterNIC The would assign IP addresses directly and also by country classification which is how we can determine a US IP address from a French one for example.

The InterNIC only assigns specific network IPs the assignment of individual network addresses is down to the system administrators who have control of those addresses.  The InterNIC has not been existence that long, prior to it’s creation the registration services where handled by NIC at nic.ddn.mil.  In 1993 the InterNIC was created to take over these services and now most use this services for the majority of network addresses,

The organisation is further subdivided into the following:

  • Registration Services
  • Database Services
  • Information Services

There are also three specific types of IP address although these aren’t linked specifically with the above organisations. These are unicast, broadcast and multicasting all subjects that will be covered in future articles on this website.

IP addresses used to be just a technical necessity and where just numbers to some extent. However nowadays an IP address will actually have many implications on what you can or can’t do. For example I tried to watch the BBC iPlayer abroad last week but it didn’t work because I had been assigned a French IP address from a Paris airport wifi i was using!

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