# DNS Resolution

lets say you know a person name but u need their phone number , dns is that conctat book that finds it for you :

here person is google.com , phone number is ip adress

DNS resolution is a process where a domain name is translated into IP adress by quering DNS server in hierarchical manner .

# DNS : The Internet’s Phonebook

DNS stand for Domain name system . it is like a internets phonebook .

human search using name like google.om , youtube.com but the computer does not understan what that shit means , computer preffered numbers to be precise ip address .

DNS act as bridge between website and user, without dns you are supposed to learn the ip adress for each and every website you want to use , which is unrealistic

## What is DNS

convert Dmain name → IP address

when you type

`youtube.com`

DNS return

`142.250.xx.xx`

dns do no load wesite it only find where he website is live

# **DNS Hierarchy**

think it as asking for direction you start from root ( main guide ) , it points you to TLD ( like a city ) , tld direct you to exact domain ( street ) and finally the domain takes you to specific host ( house )

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1768995319428/7c157da0-9c71-4e8f-8384-a61043d92a7a.png align="center")

# DNS Query Command

they manually allow yout to perform parts of DNS resolution

DNS query command allow you to

* converts domain → IP Address
    
* chexk dns record debug DNS problwms
    
* See which name server respond
    

### Some basic DNS query command

`dig`

it is more detailed query tool

it shows:

1. IP Address
    
2. Record type(A, MX, NS, CNAME)
    
3. TTL (cache time)
    
4. which DNS server replied
    
5. full DNS response secction
    

***eg dig google.com***

we use this as this show raw data , no hiding full transparency but it is long and can be heavy for beginner

`nslookup`

it is a baisc DNS liikup utility

it shows

1. Domain → IP mapping
    
2. Name server info
    

***eg nslookup google.com***

it is uses for quick checks not deep analysis

`host`

it is lightweight DNS lookup command

it shows

1. Very readable output
    
2. No extra noise
    
3. Fast checks
    

***eg host*** [***g***](http://google.com)***oogle.com***

it gaves less details than dig

# `dig` command

It is a simple command that find out a what ip adtress does a domain name get from DNS . it helps us in understanding how dns actually wotk

## used

it is used whn you want to check DNS behaviour

for example

1. wen a website is not openig :
    
    does dns returning the correct ip or is the domain resolving
    
2. when u want to find out the domains Ip address
    
3. when learning how dns actually work
    

# step by step DNS Resolution Using `dig`

## **1.Root Name Servers :** `dig . NS`

The `.` means the root of DNS system

NS asks for Name Server

so when you run `dig . NS`

you are asking who are the root DNS server ? WHere does the DNS system start

we got something like this

a.root-servers.net  
b.root-servers.net  
c.root-servers.net  
...

### Root name server → they are the special dns server present at the top of hierarchy

1. there are 13 root server name from A to M
    
2. Each gropu has multiple ohysical server worldwide
    

**why root server matter**

* They are **the starting point for all DNS resolution**.
    
* Without root servers, **no domain on the internet could be found**.
    

## 2.dig com NS -TLD Name Server

`command` dig com NS

this ask the DNS that who manages `.com` domain

their output look like

a.gtld-servers.net  
b.gtld-servers.net  
...

## 3.dig google.com NS

`command` dig google.com NS

it basically ask which server are responsible for google.com

### Authoritative Name Servers → they are the main server of website/domain:

For Google, we willl see something like:

* ns1.google.com
    
* ns2.google.com
    

These are Google’s own DNS servers.

## 4.dig google.com

`command` dig google.com

this basically ask dns that what is the ip adress of google.com

output look like

google.com → 142.250.xx.xx

## Full DNS Resolution Flow (Easy)

When you type `google.com` in browser, this happens:

### Step 1

Ask Root Server  
→ Where is .com?

### Step 2

Ask .com Server  
→ “Where is google.com

### Step 3

Ask Google’s Name Server  
→ “What is Googles IP?

### Step 4

Get IP Address  
→ Browser connects to website

In `dig` form:

```plaintext
dig . NS
↓
dig com NS
↓
dig google.com NS
↓
dig google.com
```

# what is recursive resolver

![DNS recursive resolver](https://www.cloudflare.com/img/learning/dns/dns-server-types/recursive-resolver.png align="left")

it is a DNS server that

* takes ur request
    
* find the answer step by step
    
* return the final ip to you
    

### why this exist

imagine if ur browser had to talk to 3-4 server every time, this m=is slow and inefficient