Skip to content

Networking

Packets, ports, handshakes, and the proxies in between.

IPTCPUDPHTTPHTTPSTLSDNSportssocketsfirewallsreverse proxiesVPNCDNs

Lessons

  1. 8.1TCP vs UDP (and why QUIC exists)The internet loses and shuffles packets. TCP fixes that with care and patience; UDP just sends and hopes. Here's when each wins. 30 min TCP vs UDP Latency budget
  2. 8.2HTTP and TLS: the language of the web, encryptedWhat your browser and your server actually say to each other, and how the padlock keeps strangers out of the conversation. 30 min Latency budget TCP vs UDP
  3. 8.3DNS deep dive: records, TTLs, GeoDNS and failoverDNS does more than turn names into numbers. It routes mail, steers visitors to the nearest server, and causes a surprising number of outages. 30 min The nines
  4. 8.4Proxies, load balancers, gateways and firewallsBetween your users and your servers sit a few helper boxes. Here's what each one does, and the one question that explains them all. 30 min Follow the request

On the job: try it on your own project

Ask Claude Code to map how traffic reaches your app: domain, DNS records, CDN or proxy, TLS certificate, load balancer, ports and firewall rules. Check certificate expiry dates and DNS TTLs yourself. Write a one-page network path diagram for your app, plus a note on the single point where a mistake would take everything offline.

Can you do this now?

0/4. Anything you can't tick yet: reopen that lesson's practice ladder.