TCP/IP Addressing

TCP/IP uses 32 bits, or 4 numbers between 0 and 255 to address a computer.

IP Addresses

Each computer must have an IP address before it can connect to the Internet.

Each IP packet must have an address before it can be sent to another computer.

This is an IP address: 192.68.20.50.
This might be the same IP address:  www.w3schools.com

You will learn more about IP addresses and IP names in the next chapter of this tutorial.

An IP Address Contains 4 Numbers.

This is your IP address: 38.103.63.16

TCP/IP uses 4 numbers to address a computer. Each computer must have a unique 4 number address.

The numbers are always between 0 and 255. Addresses are normally written as four numbers separated by a period like this: 192.168.1.50.

32 Bits = 4 Bytes

TCP/IP uses 32 bits addressing. One computer byte is 8 bits. So TCP/IP uses 4 computer bytes.

A computer byte can contain 256 different values:

00000000, 00000001, 00000010, 00000011, 00000100, 00000101, 00000110, 00000111, 00001000 .......and all the way up to 11111111.

Now you know why a TCP/IP address is 4 numbers between 0 and 255

Domain Names

12 digit numbers are hard to remember. Using a name is easier.

Names used for TCP/IP addresses are called domain names. w3schools.com is a domain name.

When you address a web site like http://www.w3schools.com, the name is translated to a number by a DNS process (Domain Name Server).

All over the world, a large number of DNS servers are connected to the Internet. DNS servers are responsible for translating domain names into TCP/IP addresses and update each other with new domain names.

When a new domain name is registered together with a TCP/IP address, DNS servers all over the world are updated with this information.

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