Contents · TCP/IP · frontendlabs

Part 0 — Start here (read this first)

0.1 Who this is for · 0.2 The learning flow · 0.3 The roadmap · 0.4 Set up your machine · 0.5 The tiny bit of background you need · 0.6 How to not get stuck · 0.7 The series: OS → networking → security → HTTPS · 0.8 The Go labs: setup and index

Part 1 — What is a network, really?

The problem networks solve
Layers: the postal-service idea
The four layers of TCP/IP
Our running example: what happens when you open a website

Part 2 — Your local network (the link layer) 5. MAC addresses and Ethernet frames 6. ARP: finding your neighbour 7. Switches, and what "broadcast domain" means 8. Wi-Fi: same idea, different physics

Part 3 — IP addresses and getting around the world 9. What an IP address actually is 10. Subnet masks: the part everyone finds hard 11. Subnetting practice (with answers) 12. Private addresses and NAT 13. Routing: how a packet finds its way 14. ICMP: what ping and traceroute really do 15. MTU: the maximum size of a packet 16. IPv6: why it exists and how it differs

Part 4 — Getting connected automatically 17. DHCP: how your device gets an address 18. DNS: turning names into addresses

Part 5 — Ports and the transport layer 19. Ports and sockets: which program gets the data? 20. UDP: fire and forget 21. TCP part 1: the three-way handshake 22. TCP part 2: how it never loses your data 23. TCP part 3: closing a connection, and the states

Part 6 — Making TCP fast (and why yours isn't) 24. Flow control: the sliding window 25. Congestion control: sharing the road 26. The 40-millisecond mystery (Nagle meets delayed ACK) 27. Latency, bandwidth, and why distance costs money

Part 7 — The application layer 28. HTTP: how the web actually talks 29. TLS: how it gets encrypted 30. HTTP/2 and HTTP/3

Part 8 — Seeing and fixing the network 31. tcpdump: watching packets go by 32. Wireshark: reading a conversation 33. ss: what your machine's connections are doing 34. A troubleshooting method that works 35. The five classic problems and their fingerprints

Part 9 — Modern networking 36. Load balancers, CDNs, and anycast 37. Cloud and container networking 38. Security basics

Part 10 — HTTP in depth 39. How HTTP messages are framed (and how it goes wrong) 40. Caching: the biggest performance lever there is 41. Cookies: how the web remembers you 42. CORS: why the browser blocked your request 43. WebSockets and Server-Sent Events 44. Compression, range requests, and proxies

Part 11 — Watching your network (monitoring) 45. What to measure, and why averages lie 46. Where the numbers come from: counters, flows, and probes 47. Alerts that wake you for the right reasons

Part 12 — How routers learn routes 48. Two ways to share directions 49. OSPF: finding your way inside one network 50. BGP: how the whole internet agrees on directions 51. When a router dies: VRRP and friends

Part 13 — Professional networking: operations, debugging, and design 52. Host networking internals: namespaces, veth, bridges, conntrack 53. Firewalls in the real world: host firewalls, cloud security groups, NACLs 54. VPNs and tunnels: WireGuard, IPsec, GRE, overlays, and MTU traps 55. DNS operations: authoritative DNS, delegation, split-horizon, outages 56. TLS and certificate operations: expiry, chains, SNI, rotation 57. Production load balancing: L4 vs L7, health checks, draining, retries 58. Kubernetes networking: Services, Ingress, NetworkPolicy, CNI 59. Network performance engineering: QoS, packet loss, shaping, saturation 60. Incident response: runbooks, packet evidence, and escalation 61. Network design/refactoring: migrations, diagrams, IPAM, change safety 62. Capstone lab: build, break, observe, and repair a production-like network

Part 14 — Where to go next 63. Honest gaps and a six-month plan 64. Project ideas by level 65. The series map: where every topic lives

Appendices

A. Glossary (plain language)
B. Command cheat sheet
C. Subnetting cheat sheet + practice answers
D. Ports and protocols reference
E. Reading list (books, blogs, videos, courses) + how facts were checked
F. Answers to "Check yourself"