The Journey of a DNS Call: Step-by-Step Insight into Website Loading
Have you ever wondered what exactly happens after you type “google.com” into your browser and hit Enter? On the surface, it seems instant — you see the familiar Google homepage in a fraction of a second. But behind the scenes, your browser and the internet perform a series of domain name resolution steps to find the server you’re trying to reach.
In this post, I will break down every small step in the DNS (Domain Name System) lookup and resolution process — the critical foundation that makes web browsing possible.
What Is DNS?
The Domain Name System (DNS) is often described as the internet’s phone book. It translates human-friendly domain names like google.com into machine-readable IP addresses like 142.250.190.78 so that computers can communicate over the network.
Step-by-Step DNS Resolution Process
Below are the key steps that happen every time you type a URL and press Enter:
1. User Enters the Domain Name
When you type google.com in the browser and hit Enter:
Your browser starts the navigation process.
Before any HTTP request, it must resolve the domain name into an IP address that computers understand.
2. Browser Checks Local Cache
Before making any network calls, the browser checks its internal DNS cache:
If it already recently resolved
google.com, it may have the IP cached.If the IP exists in the cache, no DNS lookup is needed — saving time.
3. Operating System Cache & Hosts File Lookup
If the browser doesn’t have it cached:
The browser asks the operating system to resolve the domain.
The OS first checks its own DNS cache.
It also checks the hosts file — a local file that can override DNS entries. GeeksforGeeks
4. Query Sent to DNS Resolver (ISP/Configured DNS Server)
If the OS also doesn’t have the IP cached:
The request is sent to a DNS resolver — usually provided by your ISP or custom DNS service (like Google DNS 8.8.8.8).
This resolver is responsible for finding the IP address for the domain on your behalf.
5. Resolver Checks Its Cache
The resolver first looks in its own cache:
Many popular domains get cached for performance.
If it finds the entry, it returns the IP immediately, and the process moves on.
6. Resolver Queries the Root DNS Servers
If the resolver doesn’t have the answer:
It sends a request to one of the Root DNS Servers.
Root servers are the highest level in DNS hierarchy and know where the Top-Level Domain (TLD) servers are (such as
.com,.org, etc.).The root server doesn’t return the final IP — instead it points the resolver to the appropriate TLD DNS server based on the domain extension (
.comin this case).
7. Resolver Queries TLD DNS Servers
Next, the resolver asks the TLD DNS server for .com domains:
The TLD servers know which Authoritative DNS servers hold records for specific domains.
For
google.com, the.comTLD server points the resolver to Google’s authoritative DNS server.
8. Resolver Queries Authoritative DNS Server
The resolver now asks the Authoritative DNS server for google.com:
This server has the final and correct DNS records.
It returns the IP address associated with the domain name.
9. Resolver Caches the Response & Sends IP Back
Once the resolver gets the IP:
It saves it in cache (for a defined TTL — Time To Live) so future lookups are faster.
It sends the IP address back to your computer’s OS.
10. Browser Receives IP and Makes HTTP(S) Request
Now that the browser has the IP address:
It uses it to send an HTTP or HTTPS request to the server at that IP.
The server responds with the website content (HTML, JavaScript, CSS, images).
Finally, the browser renders the page on your screen.
Why DNS Happens so Fast
Although this sounds like a long journey, DNS resolution often takes milliseconds because:
Caching at browser, OS, and resolver levels
Distributed servers around the world
Optimized DNS infrastructure
DNS Caching: Speeding Things Up
DNS caching is a major performance booster:
Entries can live in cache based on TTL values.
This dramatically reduces DNS resolution time for repeat visits within the cache lifespan.
The Big Picture
From typing a domain like google.com to loading the page:
Browser checks cache
OS checks cache & hosts file
Resolver looks up via recursive queries
Root → TLD → Authoritative servers return the IP
Browser connects to server using the IP
Web page content is downloaded and rendered
All in a fraction of a second.
Final Notes
Understanding DNS helps with:
Performance optimization
Debugging connectivity issues
Building reliable web applications
Knowing these steps clarifies why DNS is one of the most critical systems of the internet, serving as the backbone of web navigation.