Module 02
How data moves
See what really happens between pressing Enter and a page appearing. You follow one request down the layers, watching each one wrap the data in its own header, then back up again at the other end.
Start lesson 1
Which layer does which job? · 8 min · free, no account
PhysicalOpen now
What you'll operate
- The layer model as a working tool
- Encapsulation and decapsulation
- One request, followed end to end
- lessons
- 6
- minutes
- 50
Lessons in this module
- 1Which layer does which job?Follow one request across the network and see the four questions every device has to answer.Free, no account8 min
- 2What gets wrapped around your data?Watch each layer add its header, with the real sizes, and learn the name of every unit.Plus8 min
- 3How does the right program get it?Unwrap a frame at the server and see which field hands the contents to the next layer.Plus8 min
- 4Which addresses change along the way?Follow one packet across two routers and see what is rewritten at every hop and what never is.Plus8 min
- 5Why does a big download arrive in pieces?See how the MTU of a link decides the size of every segment, and what happens when a packet is too big.Plus9 min
- 6What happens when you press Enter?Follow one web request from the name lookup to the page, then use the sequence to find faults.Plus9 min
Lesson 1 is open to everyone, with no account. The other lessons in this module are part of Plus.