What is DNS (Domain Name System)?

 

What is Domain Name Systems

Hey everyone, what is DNS?

Have you ever wondered how you access the web pages that you do almost every other day?

I am Jessica, and I'm going to explain to you how DNS works. DNS in short is called the Domain Name System. The domain name system translates domain names to IP addresses, and what is adomain and what is an IP address?

What is DNS (Domain Name Service) ?

Domain Name Service (DNS) is a system that resolves computer addresses to human-readable names. It is used to translate domain names (like www.example.com) into IP addresses.

Let's take a look at that. First,let's see what a domain name is. A domain name is any text or string that youbasically enter in your web page.It could be ibm.com, google.com, abc.com, any of these.

And what really is an IP address? IP address is a four set number, goes like this. Justgoing to write a random number for you here.

I'm pretty sure you have allseen this IP address almostevery day when you access these websites and saysoh you know your web browser is down.

You know, you're not able to access the DNS that you're looking for.

So, let's take an example, abc.com. What happens is, instead of typing abc.

com, if youtype in the IP address of that particular websitein your web browser you will actuallybe routed to the web page.

Now, the main component of the DNS system is the DNS resolver.

What is DNS resolver?

A DNS resolver is a computer system that allows a user to search for domain names (e.g. www.google.com) and IP addresses (e.g. 104.124.124.124) using a domain name server (DNS) and an IP address.

So, the DNS resolve racts as the phone book in this entire thing. How do we bridge the gap betweenthe human communication and the DNS, and the networking world?

So, in the networking world the computersuse numbers to communicate with each other, and in the human world we use names to communicate witheach other, and here DNS resolver acts as a phonebook where you search the name and match it to the number.

What the IP address

The IP address is the internet protocol that has a set of rules that helps millions ofdevices communicate with each other and that'swhy we have these IP addresses allocatedto each and every device on the internet.

All these devices communicate using thisunique identifier, and since as humanswe are not accustomed to remembering names, weuse these domain names, to remembering numbers,we use the domain names and that's how weresolve using the DNS resolver.

Now thatwe know an overview of the domain name systemlet's take a look at how the DNS lookup happens. So the first step in the DNS lookup is the user.This is where we enter the website address fromour web page and you are going to be the actorhere.

So, the web browser has what we call thecache memory. The cache memory stores certainvalues for a certain time period of time. So, whenyou enter the address abc.com let's say, whathappens is it looks in the cache memory first andwhen we say, "oh, i don't have the IP address ofthe particular website that you're looking for,"we forward the request to the main DNS resolver.

So this is going to be our DNS resolver for the day, and now from here the DNS resolver has its own cache.

It looks at its cache and says "hey, i don't havethe IP address of the particular website that youare looking for. So what i'm going to do is i'mgoing to route your request to the root server."I'm going to use a differentcolor.

So, this is the root serverand root server is the top server atthe top level in the DNS hierarchy,and the root server still doesn't have theinformation of abc.com that you're looking for,but what it does have is the informationabout the top level domain serverthat you have to route your request to.

Also the root server is placed across different locationsthroughout the world there are almosthundreds of these root servers placed,and there are 12 different organizations thatmanage these root servers, and from there weget the top level domain server's IP address.So, now we send the request to the TLD server.

And the TLD is nothing but "Top Level Domain",which basically means it has all the informationfor the top level domain, and in thiscase the top level domain is going to bea dot com.

So it could be anything like dotnet, dot org, as such. What it does say is"hey, i don't have the ip address of abc.com, buti can send your request to the authoritative nameserver.

I can send the IP address to whichyou need to send your request to, and theauthoritative name server has all the informationand all the DNS records that we need to access.

So basically the authoritative name server renders the DNS records that we need to access. So the request is sent to the auth name server,oh and we can also call it as the domainname server, and lot of cloud providersacross all over the world provide this serverability, and you can use multitude of them.

So this is going to be our authoritative nameserver, and what the authoritative name serverdoes it sends back the IP address of theparticular website that we are looking for,and now we get the IP address back to theDNS resolver so the DNS resolver now storesit in the cache.

I store it in the cache and I send it back to the web browser,and now the web browser has the IP addressthat it was looking for. What it does is itsends the request to the particular web serverthat points in the IP address that's been sent.So, this is the web server of any particularwebsite that you're probably accessing.

In this case it is going to be abc.com.

So, nowthe web server has all the content that isneeded to display in your web page. What werender back is the content of your web page. This is the entire working of our DNS lookup andthis is what we almost do in every day when weaccess different websites all over the internet.I hope you find this video very informative. If you like this article and want tosee more like it please subscribe and stay update.

If you have questions about domain name system definition or please drop them in the comments below.

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