Hello, everyone.
So in this video, we're going to see how do we find a website on the Internet?
So we are going to take an example.
Let's say Rohit wants to use a Facebook.
So how does Rohit's computer identify the Facebook server?
How the system.
So DNS comes to the help.
DNA stands for domain name service or sometimes referred as domain name server or domain name system.
So with the help of DNS only any client is able to reach to a particular server.
For instance, Rohit is able to reach to the Facebook server and is able to serve the content into his
browser and the client side and is able to use the application.
So how does this actually work?
So we are going to see.
I highly recommend coming onto this particular website, which is how DNS works, which is beautifully
illustrated, the functioning of DNS in a cartoonist manner.
So let us start this and see over here.
Episode one, the website is unknown.
So we do not know how are we going to reach to that particular Web site.
So this is Rohit and he's going to type dnssimple.com into his browser and it's going to hit enter
Freeze computers and other devices, communicate using IP addresses to identify each other on the Internet.
And we know this, but humans can't remember IP addresses, so they use words.
So in case I asked you guys, can you tell me 10 shopping websites name?
You will quickly tell me Amazon, Flipkart, Jabong, Myntra and so on.
But if I ask you 10 website IP address, which contains a shopping or I can buy some electronics from
there, you won't be able to tell me the IP address.
Why?
Because we cannot remember numbers, but we can easily remember names.
So for our help there is DNS.
DNS brings together both of them.
That is the name and the number, but is the domain name and the IP address and gets us to our destination.
So this is how DNS works.
It was very simple, but let us understand something in more depth.
So whenever you type any particular address into your browser, for example, Rohit wants to use Facebook
and he will type Facebook dot com into his browser.
The first thing that will happen is the first request that has been checked is into the browsers.
cache.
So once the browsers cache is checked and if the website is not open earlier into the browser ever or
saved into the cache, then the request goes to the OS.
And OS also has its own cache.
Once it is not able to find into the browser or the OS cache, then the request will now go to a round
trip as the request will move or will leave the computer and now it is going to start its round trip.
All right, let's go to the next episode and see ,so the request moves out of arrowheads, computer and Rohit
house and goes out.
Now the request reaches to the resolvers inbox.
Who is the resolver?
Resolver is none other than your ISP, which is your Internet service provider that gives you Internet
service.
So once your request reaches to the ISP, that is because you want to open Facebook dot com ,sure Rohit
you can open it.
So the ISP is going to check its own cache first again.
And if he is not able to identify the website, then we are going to ask the Root!
So a road trip is going to get continued because even the resolver, which is our ISP, does not know
where is Facebook dot com.
So there is always a server is usually your ISP and we know that now.
Now our request is going to the route server the route server knows where to locate the dot com
TLD.
So dot com is basically what is added.
Behind our website, for example, Google dot com, Facebook dot com, and there are more such top-level
domains like edu.gov.in etc
Now, next, when the request reaches to the root servers, then the root server ask, what do you want?
And we are going to say here what we want to open Facebook dot com.
Do you know where can I find it?
So the root says "sorry" resolver.
I do not know where to find Facebook dot com, but I can tell you where to find them.
Dot com, top level domain server.
So now a request is going to the dot com TLD server.
So a route has different different DNS hierarchies of TLD's.
For example, as you can see a little zoom out a little bit .com , .org, .net.
And there are many such like that.
So root checks for whatever the request has came of the client, for example, as it wants to see
Facebook dot com.
So the route is only going to check the TLD.
That is the top level domain in the dot com hierarchy.
And here the route will be able to find it.
Why?
Because all the domain names which are registered has all its database saved to the root server.
So anytime you buy any domain from GoDaddy, Namecheap or anywhere in this world, always a small fee has
been taken from you, which we generally call it, as I can fee.
So your particular domain name or your particular website name are added into the root servers
hierarchy this is compulsory and that has to happen.
So basically the root root knows if any website has been made or deployed with any particular domain
name.
And finally we are able to see the particular website how once route is able to identify.
OK, Facebook dot com lies and the dot com tlt and it is pointing to IP address, let's say it points
to the IP address 10.10.10, and then route is going to say, Ok Rohit,this
I have identified Facebook.
Dot com is pointing to this IP address.
Now you can fetch Facebook.
So now Rohit is going to come back, which is taking the request or the response back to his computer.
Once he is coming back, he will keep on saving the particular response that he have got from the root
server.
In all the cases, for example, that resolver is going to say it into its cache first, then the browser
will save it as well as the OS will save it into its cache why so that the whole process or the
whole round trip does not happen again.
So I hope you guys understood how actually DNS works.
And whenever you type anything into your browser, how the request goes from your browser cache to your
OS cache, then to your resolver, then to the root and then to the server.
Thank you.