Question 1

What is a CDN?

Accepted Answer

A Content Delivery Network caches your content on servers around the world. Users load content from the nearest server ("edge") instead of your origin server. Result: faster load times globally.

Question 2

Do I really need a CDN for my startup?

Accepted Answer

If your users are global or you serve significant static content (images, JS, CSS), yes. CDNs are often free (Cloudflare) or included (Vercel). Performance impacts conversions—every second counts.

Question 3

Cloudflare, Bunny CDN, or Fastly?

Accepted Answer

Cloudflare is the default choice—generous free tier, excellent features. Bunny CDN is simple and affordable. Fastly is powerful but enterprise-focused. Vercel and Netlify include CDN by default. Start with Cloudflare.

Question 4

Is Cloudflare really free?

Accepted Answer

Yes, Cloudflare's free plan includes CDN, SSL, DDoS protection, and basic features. It's legitimately useful for most startups. Paid plans add analytics, optimization, and advanced security.

Question 5

How do I set up a CDN?

Accepted Answer

For Cloudflare: point your domain's nameservers to Cloudflare. They proxy your traffic automatically. For other CDNs: configure CNAME records to point to CDN domains. Most platforms have step-by-step guides.

Question 6

What content should be cached?

Accepted Answer

Static content: images, CSS, JavaScript, fonts. Don't cache dynamic API responses or user-specific content without careful cache headers. CDNs respect your cache-control headers.

Question 7

What are cache headers?

Accepted Answer

HTTP headers that tell browsers and CDNs how long to cache content. Cache-Control: max-age=3600 means cache for 1 hour. Set appropriate TTLs for different content types. Longer caching = better performance.

Question 8

How do I purge cached content?

Accepted Answer

CDNs have APIs and dashboards to purge cache instantly. Purge when you deploy new versions. Or use cache-busting: append version numbers to file URLs so cached versions aren't served.

Question 9

What is cache invalidation?

Accepted Answer

Telling the CDN to fetch fresh content instead of serving cached versions. Can purge by URL, tag, or entire cache. Important when content updates frequently. Some say it's one of computing's hard problems.

Question 10

What are edge functions?

Accepted Answer

Code that runs at CDN edge locations, not your origin server. Cloudflare Workers, Vercel Edge Functions. Use for fast personalization, A/B tests, and auth without origin round trips.

Question 11

How does a CDN improve security?

Accepted Answer

CDNs absorb DDoS attacks, provide free SSL, and hide your origin server IP. Cloudflare's free plan includes basic DDoS protection. Your origin only handles traffic the CDN passes through.

Question 12

What is image optimization?

Accepted Answer

CDNs can resize, compress, and format-convert images on the fly. Serve WebP to browsers that support it. Cloudflare Polish and Bunny Optimizer do this automatically. Smaller images = faster pages.

Question 13

What are Core Web Vitals?

Accepted Answer

Google's metrics for page experience: LCP (largest content load time), FID (interactivity), CLS (visual stability). CDNs improve LCP significantly. Core Web Vitals affect SEO rankings.

Question 14

How do I test CDN performance?

Accepted Answer

Use WebPageTest from different global locations. Check if resources are served from CDN (cache-status headers). Compare load times before and after CDN. Lighthouse audits show opportunities.

Question 15

What is latency and how do CDNs help?

Accepted Answer

Latency is the delay from request to response. Distance matters—requests to servers across the world take longer. CDNs put content closer to users, reducing latency. Particularly noticeable for first loads.

Question 16

Should I put my API behind a CDN?

Accepted Answer

Dynamic APIs usually aren't cached, but CDNs still help with SSL termination and protection. Some API responses can be cached (GET requests that rarely change). Evaluate on a case-by-case basis.

Question 17

What is WAF (Web Application Firewall)?

Accepted Answer

Firewall rules that block malicious web traffic: SQL injection, XSS attacks, bot abuse. Cloudflare and Fastly include WAF features. An additional security layer between the internet and your app.

Question 18

How do I handle videos?

Accepted Answer

Videos need specialized CDNs or video platforms (Mux, Cloudflare Stream). They handle transcoding, adaptive bitrate, and global delivery. Don't try to serve large videos through generic CDN—use dedicated video infrastructure.

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