Pillar 2 · Networking

Networking

How machines talk to each other. Eight guides in the full TechForge style — diagrams, quizzes, interview questions — from the TCP/IP stack to WebSockets.

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What is computer networking?

Networking is how independent machines exchange data reliably over unreliable wires and radio. Your browser, your API calls, every message app — all of it is one computer handing bytes to another through a stack of agreed-upon protocols, each layer solving one problem and trusting the layer below.

The internet is built in layers: the link moves bits between neighbours, IP routes packets across networks, TCP/UDP turn packets into reliable (or fast) streams, and HTTP/DNS/TLS give applications something useful to say. Learn the stack once and every "why is it slow / why did it fail" becomes answerable.

This is the layer under system design (load balancers, CDNs), under DevOps (ports, firewalls, DNS), and behind the most-asked interview question of all: what happens when you type a URL and hit enter?

Learning path

Eight guides, in order — diagrams, real commands, interview questions and a quiz in each.

1
The TCP/IP Stack
Four layers, what each one adds, and how a packet is wrapped and unwrapped end to end.
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2
TCP vs UDP
Handshakes, reliability, ordering, and when you deliberately choose the unreliable one.
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3
DNS
Recursive vs authoritative resolution, record types, caching and TTLs — the internet’s phonebook.
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4
HTTP & HTTPS
Methods, status codes, headers, HTTP/1.1 vs 2 vs 3, and what TLS actually encrypts.
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5
What Happens When You Type a URL
The evergreen interview question, answered layer by layer with a full diagram.
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6
Sockets & Ports
What a socket is, the accept loop, ephemeral ports, and reading netstat like a pro.
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7
IP, Subnets & Routing
CIDR notation, public vs private ranges, NAT, and how routers pick a path.
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8
WebSockets & Real-Time
Upgrading past request/response — long polling, SSE, WebSockets, and when each wins.
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