Session 1 — How Data Travels

“When you log into your bank online and transfer money, where does it go?”

That was the question your instructor opened with. Most people shrug — it goes somewhere, the money arrives, and that is enough. But “somewhere” is actually a precisely engineered journey through cables, routers, data centres, and protocols. By the end of this session, you can trace every step of that journey.

What You Will Learn

  • What a network actually is, and how devices connect to share data
  • What an IP address is and why every device on the internet needs one
  • How DNS turns a name like sbi.co.in into an address a computer can use
  • What packets are and why data is broken into small chunks before sending
  • How packets find their way across the internet (routing)
  • What protocols are and why everyone needs to agree on the same rules

The Big Idea

The internet is a physical, engineered system with rules — not magic. Every transfer of data follows the same basic process: break it into packets, address each packet, route them across hops, and reassemble at the destination. Once you see this, you start understanding why some things fail and how security fits in.

Character Focus This Session

Deepa asks the question on everyone’s mind: “But if data breaks into packets and they all take different paths, how do they arrive in the right order?”

Rohan wants to know what happens at each router hop and whether packets can get lost.

Warm-Up Check

Before reading on, try to answer these without looking anything up. There are no wrong answers — this is just to see what you already know.

  1. Your phone connects to the internet through your mobile network. But your laptop connects through Wi-Fi. Does your laptop have a different IP address than your phone on the same Wi-Fi?
  2. When you type google.com into a browser, how does it know where to send your request?
  3. If you send a 10 MB file to a friend, does it travel as one big chunk or many small pieces?

Keep your answers in mind as you read the Concepts page — you will find out if you were right.