Internet Basics - Domain Name System (DNS)

In my previous entry, we discussed IP Addresses and how difficult it would be for us to memorize so many different numbers to get to our favorite websites.  The Domain Name System (DNS) was developed to make this easier for us.  With the DNS system people can easily remember their favorite websites and still allow computers to communicate with each other using their assigned IP address.

Back to a previous example using mailing addresses, it can be similarly difficult to memorize the addresses (or phone numbers) of all your friends and family.  To assist with that, we now store contacts on our phones to easily look up the address or phone number by people's names.  Though not quite popular anymore, there are still phonebooks out there or online directories where you can search for people's addresses and phone numbers by their names.

In the same way, DNS is a phone book for the Internet.  It will translate domain names into IP addresses.

Domain Names

To understand DNS, we first need to understand Domain Names.  Let's go through some terminology.

A Domain Name is a unique name to identify a website and other Internet resources.  For example google.com is a domain name.  

You will also hear the term subdomains which are just domain names that are part of a larger domain.  Some subdomains of google.com include news.google.com or translate.google.com.

A hostname is the full domain of the website you are going to.  These full names are called Fully Qualified Domain Names.

So all the examples above are domain names: google.com, news.google.com, and translate.google.com.

News.google.com and translate.google.com are subdomains of google.com.  They are also both hostnames as they bring you to the Google news site and translation site respectively.

Still with me?  Comment below if you have questions but let's finish up DNS.

DNS

So DNS was set up to translate these domain names to IP addresses and acts similar to a phonebook or contacts list on your phone.  It's easier to remember your friend's name than their phone number.  In order to map these domains to IP addresses, someone must assign the address to the domain.

Each company typically manages their own "phonebook" or "contacts list".  Let's take Google as an example.  Google is assigned a set of IP addresses that they can use to put their web servers on the Internet.  Google may add or remove domains frequently so it's best if the manage the assignment of their IPs to their domain names.  

The management of these assignments of IP to domain names is typically done on specialized servers called name servers.  We will go more into name servers in a later post so don't worry if you don't quite understand that part yet.

Summary

To summarize the above briefly:

• DNS is a system to map domain names to IP addresses
• DNS makes it easy for humans to remember web site hostnames but still allow computers to communicate each other using assigned IP addresses

In our next post we will go through the DNS Resolution process.  This is the actual flow of what happens when you type a hostname in your computer and how your computer translates the hostname into an IP address to connect to that website.