juniorCDN
Explain CDN Caching.
Updated Apr 28, 2026
Short answer
Caching is the process of storing copies of files in a temporary storage location so that they can be accessed more quickly.
Deep explanation
CDN architecture involves a network of proxy servers. When a user requests content, the DNS routes them to the nearest Edge server. This minimizes the physical distance data travels (the 'last mile'), reducing round-trip time (RTT). Key protocols like TCP and TLS are terminated at the edge, further speeding up the handshake process.
Real-world example
A user in Tokyo accessing a website hosted in New York. Without a CDN, the request travels across the ocean. With a CDN, the user gets the image from a Tokyo-based edge server.
Common mistakes
- Thinking a CDN replaces a web host
- it actually acts as a performance layer on top of it.
Follow-up questions
- How does DNS-based routing work in CDNs?
- Can static and dynamic content both be served via CDN?