Design a Content Delivery Network (CDN)
Last Updated: December 29, 2025
What is a CDN?
A Content Delivery Network (CDN) is a globally distributed network of servers that caches and delivers content to users from locations geographically close to them.
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The core idea is to reduce latency by serving content from edge servers instead of the origin server. When a user in Tokyo requests an image from a website hosted in New York, the CDN serves it from a nearby edge server in Asia instead of fetching it across the Pacific Ocean.
Popular Examples: Cloudflare, Akamai, Amazon CloudFront, Fastly
This system design problem tests your understanding of caching, distributed systems, DNS, networking, and global-scale infrastructure.
Lets start by clarifying the requirements.
In this chapter, we will explore the high-level design of a CDN.