The DNS system is one of the most important and often overlooked pieces of the internet puzzle. If we did not have the Domain Name System, the internet would well.. collapse. No more paying bills, purchasing things, reading the newspaper or doing anything on the internet!
The first thing to know about DNS
The computers that make up the internet are set up in large and complex networks underground that communicate with eachother. They are identified using long strings of numbers known as IP addresses (Internet Protocol). DNS is amazing because it eliminates the impossible task of memorizing the IP address of every website you want to go to.
The DNS process explained
How does this work? Let’s start the journey in a web browser. when you type www.example.com you are actually searching for www.example.com. with an extra . at the end. You never see or never type this ghost . but trust us, it’s there!
The end . represents the internet’s namespace called the root. The root is where the whole DNS process begins. When you do a search for www.example.com your browser first will determine if they know what the internet protocol address is already. It could be configured on your memory or saved in your cache.
Let’s say that the browser and the operating system both have no idea about www.example.com. Your operating system will ask what is called a resolving name server for an IP address it does not know. This is either configured automatically or manually within your operating system. Your OS queries the resolving name server for www.example.com.
All resolving name servers know where to find the root name servers. (the dot a the end of every domain name) The root name servers know where to find the com name servers. The com name servers are called the top level domain name servers or TLD name servers.
The resolving name server next takes all of this information from the root name servers, puts it in it’s cache and then goes directly to the com TLD domain servers. When the resolving name server queries www.example.com, the TLD name servers know where to find the example.com name servers.
Now the authoritative name servers come into play. When a domain is purchased the registrar is told which authoritative name servers the domain should use. The organization responsible for the top level domain known as the registry, is notified to update the TLD nameservers.
The resolving name server takes a response from the TLD name server, stores it in cache and then queries the example.com name servers. The authoritative name server then finally tells the browser to go to the corresponding IP address. The operating system gives the IP to the browser and the browser leads you to the web page.
Think about this process every time you go on a web page!