What is a CDN (Content Delivery Network)?
Why Interviewers Ask This
Interviewers use this question to quickly assess whether a candidate has the foundational knowledge required for Networking development. It reveals whether you understand the building blocks that more complex concepts rely on.
Answer
A CDN (Content Delivery Network) is a geographically distributed network of servers that caches and delivers content to users from the server closest to them, reducing latency and improving performance. When you visit a CDN-backed website, a DNS query routes you to the nearest edge server (PoP — Point of Presence) rather than the origin server. Edge servers cache: static files (images, CSS, JavaScript, videos), entire web pages, and API responses. Benefits: faster loading times (content served from nearby servers), reduced origin server load, DDoS protection (absorbs attack traffic at the edge), high availability (redundant servers globally). Major CDN providers: Cloudflare, AWS CloudFront, Akamai, Fastly. CDNs are essential for large-scale web applications — nearly every major website uses a CDN.
Common Mistake
Many candidates answer correctly but can't explain the 'why'. Always be prepared to justify your answer with a concrete example or use case from your Networking experience.