CDN & Edge Computing Cheat Sheet

Key concepts, configuration patterns, and provider comparisons for content delivery networks and edge compute platforms.

2 PagesIntermediateFeb 2, 2026

AWS CloudFront Distribution (CLI)

Create a CDN distribution in front of an S3 origin.

bash

aws cloudfront create-distribution \  --origin-domain-name my-bucket.s3.amazonaws.com \  --default-root-object index.html

Cache-Control Headers

HTTP headers controlling CDN and browser caching behavior.

bash

# Cache aggressively, immutable assets (hashed filenames)Cache-Control: public, max-age=31536000, immutable# Never cache dynamic/personalized contentCache-Control: no-store# Cache but always revalidate with originCache-Control: no-cache# Cache for 1 hour, serve stale for another hour while revalidatingCache-Control: max-age=3600, stale-while-revalidate=3600

Edge Function (Cloudflare Workers)

Run JavaScript at the edge, close to the user.

javascript

export default {  async fetch(request) {    const url = new URL(request.url);    if (url.pathname === '/hello') {      return new Response('Hello from the edge!', {        headers: { 'content-type': 'text/plain' }      });    }    return fetch(request); // pass through to origin  }};

Core Concepts

Key core concepts to know.

Origin- The source server (S3, load balancer, custom server) the CDN pulls content from
Edge Location / PoP- Geographically distributed server caching content close to end users
Cache Hit Ratio- Percentage of requests served from cache vs forwarded to origin
TTL (Time to Live)- Duration a cached object remains valid before revalidation
Cache Invalidation- Manually purging cached objects before their TTL expires
Edge Compute- Running application logic (not just caching) at edge locations for lower latency

Provider Landscape

Key provider landscape to know.

Amazon CloudFront- AWS-native CDN, integrates tightly with S3, Lambda@Edge, and ACM
Cloudflare- Global CDN plus Workers (edge compute), DDoS protection, and DNS
Azure CDN / Front Door- Microsoft's CDN with global load balancing and WAF integration
Google Cloud CDN- Backed by Google's global network, integrates with Cloud Load Balancing
Fastly- Real-time CDN with instant purge and VCL-based edge logic

Pro Tip

Version static assets with content-hashed filenames (e.g. app.a1b2c3.js) and set them to 'immutable, max-age=31536000' — this lets you cache forever while still guaranteeing instant updates, since a new deploy simply produces a new filename.

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