Prerequisites: How the Internet Actually Works

Define system architectures and distinguish the core capabilities of a system from its performance, scale, availability, and reliability characteristics.

Understand the fundamental architecture decoupling consumer interfaces from centralized business logic and persistent data stores.

Trace the complete end-to-end journey of a single network packet from user click to database row mutation and DOM re-render.

Explore numerical addressing schemes, subnetting (CIDR), NAT (Network Address Translation), and why private VPCs shield internal architectures.

Demystify the phonebook of the internet, covering hierarchical tree lookups, root nameservers, TLDs, authoritative servers, TTL caching, and Anycast routing.

Understand the application protocol powering the World Wide Web, including plaintext HTTP vulnerabilities, TLS encapsulation, and status semantics.

Master the RESTful grammar of the web: Idempotency semantics, safe vs unsafe methods, status classes (2xx, 3xx, 4xx, 5xx), and caching/security headers.

Compare reliable byte streams against lightweight datagrams: flow control, congestion avoidance, head-of-line blocking, and when to pick UDP for real-time scale.

Deep dive into SYN, SYN-ACK, ACK, sequence number synchronization, state machines (ESTABLISHED, TIME_WAIT), and connection termination (FIN/RST).

Understand asymmetric vs symmetric cryptography, Diffie-Hellman Ephemeral key exchange, X.509 Certificate Authorities, and TLS 1.2 vs TLS 1.3 1-RTT/0-RTT speedups.

Understand abstraction layers in distributed networking: Layer 4 (Transport/TCP) vs Layer 7 (Application/HTTP), encapsulation, and debugging network boundaries.

Explore kernel network primitives: File descriptors, socket bindings, ephemeral port allocations, non-blocking I/O, and the C10K/C1000K concurrent connection problem.

The iconic system design capstone question: Unify keyboard interrupts, HSTS, DNS resolution, ARP, TCP handshake, TLS 1.3, HTTP routing, DB query, and DOM rendering.