System Design Card 435 — CDN and Media Delivery / Check
Concern
Static and media-heavy workloads often need edge distribution rather than central-origin delivery for acceptable performance. Image-serving, file download, and streaming content systems depend heavily on caching at the edge.
What Check means for this concern
In BASIC, the Check step is where you review the design for bottlenecks, failure modes, security gaps, observability, and cost. For CDN and Media Delivery, that means the candidate should make this concern visible at the right moment instead of bolting it on at the end.
Design move
A good move is to review and stress-test before you hand the answer over. Tie the concern back to the user flow, the workload, and the dominant trade-off. That keeps the design grounded and makes it easier for the interviewer to follow why a cache, queue, replica, partition, or rate limiter is actually necessary.
Common miss
The miss is treating global content delivery like ordinary API traffic. BASIC helps because the staged flow keeps this concern proportional to the prompt and connected to the rest of the architecture.
BASIC prompt
“When I reach the Check stage, how does CDN and Media Delivery change the architecture, the trade-offs, or the review checklist?”