1 min lesson
The edge stack: CDN, WAF, TLS, Anycast
Use "Most of that traffic is latency-sensitive and a lot of it is expensive to serve" to describe the practical rule.
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Before a request ever touches your EKS cluster, it crosses four or five edge layers. In a Cursor system-design round, the candidates who lose are the ones who jump straight to pods and ingress and skip everything that happens at the planet's surface.
Cursor's infrastructure job description calls it one of the fastest-growing developer tools in the world, and the product is a desktop app that talks to backends for indexing, retrieval and model inference. Most of that traffic is latency-sensitive and a lot of it is expensive to serve. The edge is where you decide what gets cached, what gets blocked and which region a user lands in. All of that gets settled before a request costs you compute.
Walk the path a request takes, in order. Naming the layers buys you credibility before you've designed anything.
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Full explanation
The Edge Stack, Top to Origin
Interactive diagram. Tab through its regions; each focused region shows its detail in the panel below.
Read it top-down. The request enters at the client and only the survivors reach origin. Each layer sheds or protects so the one below it does less work.
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Optional practice
Test yourself on The edge stack: CDN, WAF, TLS, Anycast
QAn interviewer asks why a CDN won't save you much on Cursor's model-completion traffic. What's the crisp answer?
QIn the edge stack, where does TLS terminate and where is abusive traffic shed?