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Computer Networks

Layers, TCP/IP and what happens on a request.

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This course has 3 lessons. Start with the first one and use the next / previous links at the bottom of each lesson — the sidebar keeps the whole course in order.

Lessons

  1. Layered models and TCP/IPHow the OSI and TCP/IP models split network work into layers, and why encapsulation is the idea that lets every level be replaced independently.
  2. HTTP and DNS in practiceName resolution from stub resolver to authoritative server, the record types that matter, and how HTTP/1.1, HTTP/2 and HTTP/3 differ on the wire.
  3. One page request, end to endThe full path from typing a URL to a rendered page: DNS, TCP, TLS, HTTP, subresources, and where the milliseconds actually go.

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Last refreshed 2026-09-17.