Networking, DNS, Load Balancing, API Gateway
In this lesson we follow the journey of a single request, from the moment you press a button until it reaches the right server. We'll meet DNS (the phone book of the internet — it translates an address like example.com into a computer's IP number), load balancers (a component that takes incoming req
System Design is like planning a whole city: roads that carry the traffic, warehouses that store things, traffic lights that keep the flow orderly, and maintenance crews that fix problems — all so the city keeps running smoothly even at rush hour, when everyone is out at once.
- Traffic routing
- The core skill of this lesson: understanding how a request is routed to the right destination. It covers DNS (which translates a web address into an IP), load balancers (which split requests across servers), the API gateway (a single front door handling security and routing), and the request path (the request's full route). Like a postal service making sure each letter reaches the right address.
- Trade-off
- A conscious choice between two options, where each has an upside but also a price. There's no perfect answer — you pick what fits and explain to the interviewer what you gain and what you give up. Like choosing between a fast, pricey route and a cheap, slow one.
- Operational metric
- A number you can measure to tell whether a decision actually works once the system is live and serving real users (production). For example: latency (how long a response takes to come back), error rate (the share of requests that fail), queue lag (how many tasks are waiting in line), cache hit ratio (how often we found the answer ready in a fast temporary store), and more.
