networking

4 posts

Load Balancing: One Front Door for a Fleet That Keeps Changing

A single server melts under Black-Friday traffic. Load balancing is how you put ten servers behind one address — and the L4-vs-L7 choice, the routing algorithm, and the health checks are where systems live or die.

Asked at Amazon, Google, Netflix +3

Aug 8, 2026·16 min read

Mediumhigh level design distributed systems networking

CDNs: Move the Bytes to the User, Not the User to the Bytes

A user in Sydney pays ~200ms to reach a Virginia origin before any work happens — physics you can't code around. This is how CDNs cheat the speed of light with edge PoPs, anycast routing, and HTTP caching.

Asked at Cloudflare, Akamai, Fastly +3

Aug 8, 2026·16 min read

Mediumhigh level design distributed systems networking

Rate Limiting: How a Bucket of Tokens Keeps Your API Alive

One misbehaving client with a retry loop can take down a service faster than any DDoS. Rate limiting is the cheap, boring control that decides who gets served — here's how the five classic algorithms actually work, and how to make one correct across a fleet.

Asked at Stripe, Cloudflare, GitHub +2

Aug 8, 2026·16 min read

Mediumhigh level design distributed systems networking

Real-Time Updates: Polling, Long Polling, SSE, and WebSockets

HTTP can't push — the server only answers when asked. Here's the ladder of techniques that fake or fix that, each one solving the last one's flaw, and the fan-out problem that breaks all of them at scale.

Asked at Slack, Discord, WhatsApp +3

Aug 8, 2026·16 min read