cdn

Latency budgets decide architecture, and most teams buy edge compute before earning it with caching and protocol work. Know which rung of the ladder your problem actually needs.

A deceptively deep question, because there are at least six places a version can get stuck and they span the pipeline, the cluster and the edge. Work the path in order.

Purges act on exact cache keys, and the edge is full of variants the purge never named. Verify per variant at real POPs, then fix the key model instead of chasing URLs forever.

Volumetric floods die at the anycast edge; everything else reaches your origin anyway. The origin leak, expensive endpoints and unproxied surfaces decide whether a CDN is armour or decoration.

The catalog is the easy half. The scored half is stampede dynamics: one hot key expiring can multiply origin load by a thousand in a second, and there are three distinct fixes.

The app server that proxies uploads through itself is the design that fails this question. Direct-to-storage, validate after arrival, and make CDN invalidation almost never necessary.

Ladders and player logic are the warm-up. Cache topology, egress arithmetic, and knowing which quality metric actually predicts churn are what separate the answers.

Data transfer appears on nobody's architecture diagram and reliably appears on the invoice. The strong answer enumerates the taxed flows, ranks the levers, and knows which tax is worth paying.