Tutorials System Design Tutorial
CDN Caching Strategies — Complete Guide
CDN Caching Strategies — Complete Guide: free step-by-step lesson with examples, common mistakes, and interview tips — part of System Design Tutorial on Toolliyo Academy.
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System Design Tutorial · Lesson 33 of 100
CDN Caching Strategies
Basics → Scale → Interview
Basics · 1 — Building blocks · ~6 min · Module 4: Caching and Storage
What is this?
CDN caching strategies set what is cached, for how long, and how you purge — Cache-Control, surrogate keys, versioned URLs.
Why should you care?
Wrong CDN rules either stale ShopNest prices or never cache, wasting origin.
See it live — copy this example
Sketch the architecture on paper. These lessons focus on concepts and trade-offs.
Cache-Control: public, max-age=31536000, immutable (hashed app.js)
Cache-Control: public, max-age=60 (product image)
Cache-Control: private, no-store (personalized cart HTML)
Purge: surrogate-key product-42 on price changeRun Example »
This lesson uses terminal or setup steps. Run commands on your computer — the live editor appears on coding lessons.
What happened?
- Immutable hashed assets get year-long TTLs.
- Images moderate.
- Personalized HTML stays private.
- Purge APIs fix urgent wrong content.
Practice next
- Classify three ShopNest responses by cache policy.
- Version static assets by hash in the filename.
- Design purge on price update.
- Add stale-while-revalidate for images.
- Log CDN HIT/MISS ratios.
Remember
Policy follows content type. Versioning beats panic purge for static. Personal data stays private.
Price-aware purge
ShopNest purges product images/metadata when price changes.
Outcome: Shoppers see new prices without tiny global TTLs.
Interview prep for this lesson
Practice these questions aloud after reading—each links to a full structured answer.
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