How the internet works 

January 7, 2024

In the digital age, the internet is an essential part of our daily lives, shaping the way we communicate, access information, and conduct business. Let us delve into the fascinating journey of how we use the internet from a user  angle while uncovering the intricate layers that make this global network work for us seamlessly.

User Perspective:

At the surface level, using the internet appears as simple as typing a web address or tapping a link. However, beneath this user-friendly facade lies a complex web of technologies working tirelessly to deliver the desired information.

When you enter a website address, your device initiates a series of steps.

  1. Request: When you type a website address or click a link, your device sends a request to a server. It’s like asking, “Hey, can I see this website?”
  2. DNS (Domain Name System): The server might have a numerical address, but we use domain names (like www.example.com). DNS translates the name into an IP address, allowing your device to find the server.
  3. Server Connection: Your request reaches the server, which is a powerful computer storing website information. It processes your request and sends back the data your device needs.
  4. Data Transfer: The information travels back to your device through the internet, often in small pieces called packets. These packets follow the most efficient route to reach you.
  5. Rendering: Your device receives the packets and your browser / mobile app puts them together to display the website or content you requested.

It’s like sending and receiving letters, but super fast and using a complex system of computers and connections!

Behind the scenes, the internet operates on a five-layer networking model known as the OSI model*. Each layer plays a crucial role in ensuring the seamless flow of data across the digital landscape.

Networking Layers:

1. Physical Layer – Constructing the Digital Roads:

At the foundational level, the physical layer deals with the hardware and signals – the cables, switches, wireless signal tower etc. It is the reconstructions in-between analog and digital signal that builds the roads to facilitate the movement of data.

2. Data Link Layer – Traffic Rules and Signals:

Much like the traffic rules and signals on a road, the data link layer establishes a reliable link between directly connected nodes. It handles issues like error detection, ensuring smooth data flow.

3. Network Layer – Guiding Data with Street Signs:

The network layer, analogous to street signs and maps, determines the best route for data using logical addresses (IP addresses). It is the guide that directs data packets to their intended destinations.

4. Transport Layer – Managing Traffic Flow:

Comparable to managing the flow of traffic on a road, the transport layer ensures end-to-end communication. It deals with data segmentation, flow control, and error recovery, guaranteeing a smooth journey for data.

5. Application Layer – Interaction and Destination:

At the top, the application layer is where users interact with the internet. It provides network services directly to end-users or applications – the destination where people engage with the digital road system.

In conclusion, the internet, from a user perspective, is a seamless experience, masking the intricate dance of technologies beneath the surface. Understanding the networking layers sheds light on the remarkable orchestration of hardware and protocols that enable us to navigate the vast digital landscape effortlessly. 

As we continue to embrace the wonders of the internet, it is worth appreciating the complexity that ensures our online experiences remain magical.

Postscript:
During my era of undergraduate studies, we were taught the 5 layers (Internet protocol stack) when official OSI model actually has 7. 

Textbook we were using was Computer Networking: A Top-Down Approach, 7th Edition, which was last updated 2017… quite outdated to be honest.

5 layers (Internet protocol stack) versus official OSI model:
Figure 1.23 Early official document RFC1122 only introduce 4 layers.

I am glad that I really start writing this kind of educational blog, which also urge myself for continuous life learning as well.