Internet Names

The internet is based on two main protocols to control the communication. These are the Transmission Control Protocol (TCP) and the Internet Protocol (IP). Together these are known as TCP/IP. These describe a set of rules controlling how 2 computers locate each other, agree on transmission details and send bits. We are mostly interested in how the computers locate each other. Every computer on the web has a name and there are rules about what the names mean and how to use them.

Every machine is assigned a 32 bit number as an identifier. This is called the IP address. Since 32 bit binary numbers are hard to remember so they are usually written as 4 8 bit numbers, translated to decimal and separated by periods. For example, 192.66.12.1. Just for fun, let's translate to binary. Take each number between the periods and translate to binary and paste them all together.
DecimalBinary
192 11000000
66 01000010
12 00001100
1 00000001
So, 192.66.12.1 translates to 11000000010000100000110000000001.

With 32 bits, there are over 4 billion addresses, which seems like a lot. But there are a lot of computers already and even more things are being connected to the internet as we speak. The next generation of IP will have 128 bits. This give something like 3x1038 addresses. I read somewhere that this was several thousand address for every square meter of the Earths surface, oceans included. That should last for a while.

But IP addresses in any form are hard to remember. The Domain Name System (DNS) helps with this. Each machine has a name that has two parts. The first part is the host name and the second is the domain name. These two parts are separated by periods. The host name is something like depaul or xnet and could have multiple parts like cs.depaul or typhoon.xnet.

A domain is a subset of all the internet machines. Each domain has a name server. The name server is a computer that maintains lists of the machines that are part of its domain and their IP addresses. It is used to translate the host names into IP addresses. The name server (there may be more than one) in one domain can communicate with the others so if one can't figure out the name, another can.

There are domains for different kinds of institutions like com, edu and mil, or countries like de, jp or us or groups like .org. There are others, some created to provide more names. The host name must be unique within a domain. There can only be one kentarchie.com but there could be a kentarchie.com and a kentarchie.org that refer to different computers.