Networking from Scratch (lesson 9) — the seven OSI layers and four TCP/IP layers explained, the mapping between them, why both models exist, why engineers think in TCP/IP and name in OSI numbers, encapsulation in action, a layer-by-layer troubleshooting checklist, and the obligatory layer-8 joke.
Networking from Scratch (lesson 5) — the difference between switches and routers in plain English, with the MAC table vs routing table side by side, a packet walked end-to-end through both, and why your home box is secretly two devices crammed into one chassis.
Networking from Scratch (lesson 4) — the DHCP DORA four-packet exchange, lease and renewal mechanics, common DHCP options, the cross-subnet relay agent, and the ARP request/reply that turns an IP into the MAC the wire actually delivers to. Plus the symptoms of common failure modes.
Networking from Scratch (lesson 1) — an end-to-end walkthrough of the eight things that happen between clicking a link and seeing the page on your screen. DNS, ARP, routing, TCP, TLS, HTTP, render, and where to look when each one breaks. No prior experience required.
