Overview
Your complete guide to How data moves
Subnetting, transport with TCP and UDP, switching inside a network, routing between networks, dynamic routing with OSPF, then the journey of opening a site from start to end.
Non-technical and technical learners alike. Every part opens two ways in: a plain path built on an analogy for someone starting from zero, and a detailed path for someone who knows the basics and wants depth.
An animation, then what you need before you start, then the idea with code you run, then a worked example, then review cards and "test your understanding" questions.
Do not leave a part before you can answer its questions without guessing. Reading alone proves nothing.
Pick a topic
A look at How data moves
You master subnetting first, then follow the packet from the port to the switch to the router, and tie it all together in the journey of opening a site.
| Part | Topic | You learn |
|---|---|---|
| 1 | Subnets: masks and splitting a network | Prefix and mask, block size, network and broadcast addresses, equal splits and VLSM |
| 2 | Transport: TCP, UDP and ports | Ports and sockets, TCP with handshake and acknowledgements, UDP and QUIC, common ports |
| 3 | Switching and VLANs | The MAC table and flooding, VLANs, trunks and the 802.1Q tag, routing between VLANs, STP and EtherChannel |
| 4 | Routing and address translation (NAT) | The routing table, longest match, administrative distance, OSPF and BGP, NAT and PAT |
| 5 | Dynamic routing: OSPF step by step | Static against dynamic routes, Hello and neighbours, LSAs and the LSDB, Dijkstra and cost, area 0, DR and BDR, verification commands |
| 6 | What happens when you open a website? | DHCP and DORA, DNS with the resolver and cache, TLS 1.3 and certificates, HTTP and status codes, why distance slows things down |
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