BeginnerPhone
2 min

Purpose of a CDN

WebPerformanceNetworking
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Interview Question

What problem does a CDN solve and how does it improve user-perceived performance?

Key Points to Cover
  • Caches static content at edge locations closer to users
  • Reduces latency and origin bandwidth
  • Can provide TLS termination, DDoS protection, and compression
Evaluation Rubric
Explains edge caching/latency reduction40% weight
Mentions origin offload/bandwidth30% weight
Notes extra features (TLS/DDoS/compress)30% weight
Hints
  • 💡Think cache hit ratio and TTLs.
Common Pitfalls to Avoid
  • ⚠️Failing to explain *why* edge locations help (i.e., reducing physical distance and latency).
  • ⚠️Overlooking the benefit of reducing load and bandwidth on the *origin server*, focusing solely on user experience.
  • ⚠️Not clearly differentiating between static content (cached) and dynamic content (typically not cached by default).
  • ⚠️Missing key additional services like TLS termination, DDoS protection, or compression capabilities.
  • ⚠️Using technical jargon like 'PoP' or 'RTT' without a brief, beginner-friendly explanation.
Potential Follow-up Questions
  • How do cache-control headers affect CDNs?
  • What about dynamic content?
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