How DNS Resolution Works
DNS is the Internet’s phonebook
The internet runs on IP addresses.
Humans run on names.
DNS exists to bridge that gap.
DNS is the phonebook of the internet.
When you type google.com in a browser, the browser does not magically know where Google lives.
It needs to resolve the name into an IP address.
That process is called DNS resolution.
This article explains how that resolution actually works, layer by layer, using a real diagnostic tool called dig.
Why name resolution exists at all
Imagine if you had to remember this every time:
142.250.195.46
Instead of:
google.com
Name resolution exists because:
IPs change
names are stable
Humans are bad at numbers
DNS gives us human-friendly naming with machine-level precision.
Introducing dig
dig stands for Domain Information Groper.
Think of it as:
a tool that lets you inspect how DNS resolution works, step by step.
Browsers hide DNS from you.dig exposes it.
You use dig when you want to:
debug DNS issues
understand where a domain is resolved from
Inspect name servers
learn how resolution actually happens
DNS resolution happens in layers
DNS is hierarchical.
No single server knows everything.
Resolution happens in this order:
Root name servers
TLD (Top Level Domain) name servers (.com, .org, .in)
Authoritative name servers (domain owner)
Let us walk through this using dig.
Step 1: Root name servers
dig . NS
This asks:
“Who are the name servers for the root of DNS?”
The dot . represents the DNS root.
What root servers do
They do not know the IPs for Google.com
They only know where TLDs live
Think of root servers as:
a receptionist who only tells you which department to visit
Root servers point you to TLD servers.
Step 2: TLD name servers
dig com NS
This asks:
“Who manages domains ending with .com?”
TLD servers:
do not know IPs either
know which authoritative servers handle each domain
Analogy:
You reached the correct building, now you are told which office owns which file.
Step 3: Authoritative name servers
dig google.com NS
This asks:
“Which name servers are responsible for google.com?”
These servers are authoritative.
They own the DNS records for the domain.
They know:
A records
AAAA records
MX records
TXT records
This is the final authority.
Why NS records matter so much
NS records define delegation of responsibility.
They answer:
“Who is allowed to speak the truth for this domain?”
Without correct NS records:
DNS breaks
Websites go offline
Email stops working
This is why DNS changes can be dangerous if done blindly.
Step 4: Full resolution
dig google.com
This performs the complete DNS resolution.
Behind the scenes, a recursive resolver:
asks root servers
asks TLD servers
asks authoritative servers
Returns the final IP
Your browser usually talks to a recursive resolver provided by:
your ISP
Google DNS
Cloudflare DNS
You do not see these steps, but they happen every time.
How this connects to real browser requests
When you open a website:
The browser asks the OS for the IP
OS asks the recursive resolver
Resolver performs DNS resolution
IP is returned
The browser connects to the server
DNS resolution always happens before HTTP.
No DNS, no website.
System design perspective: why DNS scales
DNS works at a global scale because:
Responsibility is distributed
Caching reduces load
No single point knows everything
Hierarchy limits blast radius
Key takeaways
DNS is hierarchical, not flat
Name resolution happens in layers
Root servers guide, not answer
Authoritative servers own the truth
Recursive resolvers do the hard work for clients
diglets you see what browsers hide
If you understand this flow, DNS stops being mysterious.
