Computer Networks
Foundational concepts — the shortest path into the topic. 21 topics across 5 chapters.
Network Stack Basics
4 topicsOSI 7-Layer Model
The textbook standard for network layering — seven layers, each with one job; theoretically clean, engineering reality differs.
Encapsulation & De-encapsulation
On the way down the stack, every layer wraps the previous one in its own envelope.
TCP/IP Model
The layering the real internet uses — application / transport / network / link / physical.
Physical & Link Layer (quick tour)
Cables, fibre, Wi-Fi, switches — where data actually flows over copper / glass / radio.
Addressing & Location
7 topicsIP Address (IPv4 Basics)
Every internet host's 'house number' — how packets find their destination.
MAC Address
A NIC's 48-bit hardware address — the 'physical ID' that only matters within a LAN.
ARP (Address Resolution Protocol)
The 'IP → MAC' lookup protocol on a LAN — the hidden prerequisite for IP communication.
Subnet & CIDR
Slicing an IP range into subnets — decides who talks directly and who must go through a router.
NAT (Network Address Translation)
Why dozens of home devices share one public IP and still reach the internet — NAT.
ICMP (Internet Control Message Protocol)
The network layer's 'support desk' — Ping, Traceroute, and unreachable notifications all ride on it.
DHCP (Dynamic Host Configuration Protocol)
Plug into Wi-Fi and seconds later you have an IP — that's DHCP doing the work.
Transport Layer
4 topicsTCP (Transmission Control Protocol)
Connection-oriented, reliable, in-order, with built-in flow and congestion control — the default transport for most of the internet.
Port
One machine, one IP, many services — ports tell them apart.
UDP (User Datagram Protocol)
Connectionless, no guarantees, ultra-light — DNS, video calls, games, QUIC all rely on it.
TCP vs UDP (Comparison)
When to use TCP, when to use UDP — one table + a few rules of thumb.
Application Layer Basics
4 topicsDNS (Domain Name System)
Translates human-readable domain names into machine-usable IPs — the internet's phone book.
HTTP Basics
The language of the web — how browsers talk to servers.
HTTPS
HTTP over TLS — wraps HTTP in an encrypted channel to defeat ISP snooping and MITM tampering.
TLS (Transport Layer Security)
The de-facto standard for modern encrypted communication — HTTPS / SMTPS / IMAPS / DoT all run on it.