To know what the Internet is first we've to know about Computer Networks. Simply put, two or more computers connected is a computer network. The Internet is basically a collection of these computer networks.

These computers are connected either by cables or a wireless connection. The computer network is mainly used for resource sharing & communication purposes.

Now let's talk about how it's actually working.

If we write facebook.com in the browser. browser opens Facebook's web page for us. But how browser do it? How does it know what is facebook.com?

If we take an example-

Your friend's name is Google & you want to visit his home. What do you've to know?

His address right?? Here, either you know the address already Or, You've to check the address somewhere it's written. The same applies here to browsers.

In a computer network, the site's true address is a clump of numbers called IP address.

it's written in format of "X.X.X.X" Example: Google's IP address -

But for us, it's not possible to remember the IP address as it's written in numerical format.

In the network we have DNS(Domain Name System) it's a system that stores domain names with their corresponding IP address. Examples :

domain name - facebook.com

IP address - 69.63.176.13

“DNS is like a phone book and helps us to provide the IP address that is associated with the domain name just like our phone book gives a mobile number which is associated with the person’s name.”

How browser resolve the IP address that is associated with the domain name?

Here on the computer, After hitting the URL (address of the place) The browser cache is checked, it checks whether you've visited the website previously or not!

If you've visited then - At first, the DNS query runs to find the IP address associated with the domain name then runs in the OS cache it gets resolved.

Possible cases-

1)

DNS query runs → find for IP associated with the domain name → found → resolved!

2)

DNS query runs → find for IP associated with the domain name → not found → query runs in OS cache → found → resolved!

Now, If in the above steps, a DNS query does not get resolved -

It takes the help of resolver server or ISP (INTERNET SERVICE PROVIDER)

DNS query →(sent)→ISP→query runs in ISP Cache→gets resolved!

If no results found -

Then request send to the root server.

✷ There it never says “no results found”

it tells, from where this information you can get.

If you are searching IP address of TLD (ex- .com,.net, .Gov,. org)

→ root server tells to search in TLD (top-level domain)server

→resolver asks TLD server to give IP address of our domain name.

→TLD stores address information of domain name.

→TLD tells the resolver to ask it to Authoritative Name server.

→resolver (ISP) gets the IP address associated with the domain name and sends it back to the browser.

After getting an IP address, the resolver stores it in its cache.

so that next time, if the same query comes, it does not have to search again & follow all these steps. It can now provide an IP address from its cache.

That's how it resolves the IP address that is associated with the domain name.

Thanks for Reading (◔‿◔)!