How real systems work under the hood — databases, caches, queues, networking and the trade-offs behind them.
How the internet is actually built: undersea cables, ISPs, exchange points, BGP, DNS, data centers and CDNs, and who runs each layer of the global network.
Learn system design from the ground up — requirements, estimation, APIs, data storage, caching, queues, scaling, consistency, reliability, observability and how to reason about trade-offs.
A step-by-step walkthrough of what happens when you type a URL — DNS, TCP, TLS, HTTP, CDNs, load balancers, servers, databases and browser rendering — and where latency comes from.
Understand database indexing — B-tree internals, composite index column order, covering indexes, partial and expression indexes, reading EXPLAIN plans, and the costs of over-indexing.
SQL vs NoSQL explained — relational vs document, key-value, wide-column and graph databases, consistency, scaling, schema flexibility, and a practical guide to choosing a database.
A practical guide to caching — where to cache, cache-aside vs read-through vs write-through vs write-behind, TTLs, invalidation, stampedes, eviction policies and Redis patterns.
How message queues work and why they matter — async processing, decoupling, delivery guarantees, idempotent consumers, dead-letter queues, ordering, and choosing RabbitMQ, SQS or Kafka.
The CAP theorem in plain English — what consistency, availability and partition tolerance really mean, PACELC, strong vs eventual consistency, quorums, and how to apply it in real designs.
A complete system design walkthrough for a URL shortener like bit.ly — requirements, estimation, API, ID generation, database choice, caching, redirects, analytics and scaling.
Load balancers explained — layer 4 vs layer 7, balancing algorithms, health checks, TLS termination, sticky sessions, connection draining, global load balancing and common pitfalls.
A practical guide to event-driven architecture — events vs commands, pub/sub, event notification vs event-carried state, sagas, event sourcing, CQRS, schema evolution and debugging.