How DNS Resolution Works
If you have ever typed google.com in your browser and the page opened, DNS was working silently in the background.
Most people use the internet every day, but very few know how a website name turns into a server IP address.
That is exactly what DNS resolution does.
In this article, we will understand DNS resolution step by step using the dig command.
DNS: The Internet’s Phonebook
Computers do not understand website names like google.com.
They understand IP addresses, like 142.250.190.14.
DNS (Domain Name System) is like a phonebook:
You give a name →
google.comDNS finds the number → IP address
Your browser connects to that IP
Without DNS, we would have to remember IP addresses for every website. That would be painful.
Why Name Resolution Exists
Name resolution exists because:
Names are easy for humans to remember
IP addresses are easy for machines to use
DNS connects humans and machines
So DNS acts as a translator between names and IPs.
What is the dig Command?
dig stands for Domain Information Groper.
It is a command-line tool used to:
Check DNS records
Debug DNS problems
Understand how DNS resolution works
Developers and system engineers use dig to see what is happening behind the scenes.
Example:
dig google.com
This command shows how DNS finds the IP for google.com.
DNS Resolution Happens in Layers
DNS resolution does not happen in one step.
It happens in layers:
Root servers
↓
TLD servers (.com, .org, .in)
↓
Authoritative name servers
Let’s walk through each layer using dig.
Understanding dig . NS (Root Name Servers)
Command:
dig . NS
What this means:
.represents the root of DNSNSmeans Name Servers
This command shows the root name servers of the internet.
Why Root Servers Matter
Root servers do not know IPs of websites
They only know where TLD servers are
They are the first stop in DNS resolution
Think of root servers as:
“I don’t know google.com, but I know who manages
.com.”
Understanding dig com NS (TLD Name Servers)
Command:
dig com NS
This asks:
“Who is responsible for
.comdomains?”
The answer is TLD name servers.
What TLD Servers Do
They manage domains under
.comThey do not know IP addresses
They know which authoritative server owns a domain
Example:
“google.com is managed by these name servers.”
Understanding dig google.com NS (Authoritative Name Servers)
Command:
dig google.com NS
This shows the authoritative name servers for google.com.
Why Authoritative Servers Are Important
These servers have the final truth
They store DNS records like:
A record
AAAA record
MX record
If you want the real IP of google.com, this is where it comes from.
Understanding dig google.com (Full DNS Resolution)
Command:
dig google.com
This is what usually happens when your browser makes a request.
Behind the scenes:
Browser asks the recursive resolver
Resolver checks cache
If not found:
Ask root server
Ask TLD server
Ask authoritative server
Get IP address
Return IP to browser
Browser connects to the server
All this happens in milliseconds.
How Recursive Resolvers Work
You usually don’t talk to root servers directly.
Your system talks to a recursive resolver (ISP or public DNS).
The resolver:
Does the full DNS lookup
Caches the result
Saves time for future requests
That’s why websites often load faster the second time.
Connecting dig to Real Browser Requests
When you type google.com in your browser:
The browser is doing what
diggoogle.comshowsDNS resolution happens first
Only after getting the IP does HTTP/HTTPS start
No DNS = No website loading.
Why NS Records Matter
NS records tell:
Who is responsible for a domain
Where DNS queries should go next
Without NS records:
DNS resolution would break
The chain of trust would be lost
That’s why NS records are critical in system design.
Simple Mental Model to Remember
Think of DNS like asking directions:
Ask city map (root)
Ask area guide (TLD)
Ask house owner (authoritative)
Get exact address (IP)