Domain Name Server or DNS 1

Domain Name System (DNS)

Every internet user has heard about Domain Name Server or DNS. Sometimes when your internet is not working you might get a DNS error.
Users having static IP need to enter a server address in the DNS while setting up their connection.
Where as users having Dynamic IP, the DHCP server sends the address of DNS server along with the IP it assigned to that machine.

For users with static IP

In this we will just talk about DNS in Brief. Not in detail. Just what DNS is and how DNS helps us.

Here’s a short description of DNS Server:
Say your Boss (Client) asks you (Browser) to get a package (Get a webpage).
All these events will take place then :

DNS real life example

What IS DNS server?
We know Computer never understands words. If they did understood, English would be our standard language to write programs, instead of C, C++, java, Python etc.
Your machine talks and works only in binary language, i.e. 0 & 1.

The most basic thing you need to understand is every website is actually an IP address.

DNS are those machines who keep a table of various websites with their respective IP addresses.
Popular websites or websites that we often visit, are in cache memory of these DNS servers, so if any request comes for these, it can quickly respond by checking in cache memory.
As we know, there are millions of websites so we don’t have just one DNS server. There are many servers, about which we will see in the next post.

If you read the earlier post about Internet Protocol/IP or you have a basic knowledge about it, you would know for communication between various computers IP is used.
The name they have given is to the websites, is to make things easier for us to remember.

Imagine typing in your browser :
http://74.125.224.72/ instead of www.google.com or
http://31.13.80.1/ instead of www.facebook.com.
Pretty tough right?

Normal scenario of DNS Server

The above figure shows what happens when you enter a new URL in your browser.

But What happens when you enter ‘www.google.com’ or ‘www.yahoo.com’?
Well, actually nothing. Your browser will just take the bunch of letters that you just entered  to a DNS server and ask him,
“Can you please tell me the IP of ‘www.google.com?”

And the DNS server would be like
“Sure. Let me check it first.”

And when it finds a match it sends the IP address of that website (74.125.224.72 in-case of Google and 31.13.80.1 in case of Facebook) to our browser.

If one DNS server doesn’t has the IP of Google, it will query another DNS server for the same.
The Second DNS server will check it’s table entries for it and if the IP of that website is found, it will give it to the First DNS server, which will then send it to back to our browser.

WITHOUT DNS INTERNET WON’T FUNCTION AT ALL.

Our browser then sends a request to that IP for webpage and Google or Facebook’s web-server and it answers our request with their homepage.
Once you access Google.com, your browser will keep it in its cache memory so that it does not has to ask for its address each time you enter Google.com.
The next time you try Google, the browser will check its cache memory, will find it there and give you the webpage.

There are public DNS of Google with IP 4.4.4.4 and 8.8.8.8.
People using Dynamic IP too can use these DNS addresses.
This is how DNS works, in short.
For more detailed and In-depth process check this post.