topic 04
From bits on a wire to TLS 1.3 — the journey of one packet, retold for senior engineers.
How bits become electricity, light, or radio — and what limits them.
How a packet finds its way across millions of independent networks, what the IP header carries, and where datagrams die.
What SYN, SYN-ACK, and ACK actually negotiate — and why a connection's first RTT decides the speed of every request on it.
How a recursive resolver climbs the root → TLD → authoritative tree to turn google.com into an IP, and where caches and DNSSEC live.
How ClientHello key shares plus a certificate verifier collapse the old TLS 1.2 two-RTT handshake into one — and what 0-RTT actually buys you.
How HTTP evolved from serial request-response to multiplexed streams to QUIC datagrams — and what each version costs to run in production.
How edge servers, cache hierarchies, and smart routing cooperate to deliver content in 20 ms instead of 200 ms — and what breaks when any layer is misconfigured.
How WebSocket upgrades an HTTP connection to a persistent full-duplex channel — and everything that breaks when 10,000 slow clients pile into one broadcast server.
A reverse proxy opens two TCP connections per request so it can route, health-check, and scale backends invisibly — and every load balancing decision from round-robin to consistent hashing is a tradeoff between speed, fairness, and state.
QUIC fuses UDP, TLS 1.3, and multiplexed streams in user space — giving 1-RTT handshakes, HoL-free streams, and connection migration, at the cost of 15–30% more CPU per byte than kernel TCP.
DDoS attacks, amplification floods, and infrastructure-layer hijacks (DNS/BGP) are defeated by layered defenses — anycast edge absorption, rate limiting, WAF, mTLS, and RPKI/ROV — because no single defense stops all vectors.
Every layer from DNS to circuit breaker fires on every request — the capstone chapter shows how they compose, fail, and recover as a system.
Every unit, from the underground to the orbit. Networking & Protocols is one constellation in the atlas — climb another topic and watch the next one light up.