CDN Caching: CloudFront Distribution Strategy
This article explains how we use CloudFront CDN to cache content and improve global performance.
The Problem: Global Latency
Users access our website from around the world:
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India: 50ms latency
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USA: 200ms latency
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Europe: 250ms latency
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Asia: 150ms latency
Serving all traffic from India causes slow page loads for international users.
The Solution: CloudFront CDN
CloudFront: AWS Content Delivery Network
Edge locations: 400+ locations worldwide
Benefit: Content served from nearest location
What Gets Cached
Static Assets (Long TTL)
Content: Images, CSS, JavaScript, fonts
TTL: 1 year
Path: /s/*
Benefit: Rarely changes, cache aggressively
Product Pages (Medium TTL)
Content: Product specifications, images
TTL: 1 hour
Path: /p/*
Benefit: Balance freshness and performance
Query Pages (Short TTL)
Content: Search results, filtered views
TTL: 5 minutes
Path: /q/*
Benefit: Frequent updates, short cache
Articles (Long TTL)
Content: Technical documentation
TTL: 24 hours
Path: /a/*
Benefit: Rarely changes
What's NOT Cached
Dynamic content:
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Search results (
/q/?q=<query>) -
User-specific content (cart, account)
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API endpoints (
/api/*)
Reason: Must be fresh, user-specific
Cache Behavior
Cache Key
CloudFront uses URL as cache key:
Same URL: Served from cache
Different URL: New cache entry
Query parameters: Included in key (except tracking params)
Cache Headers
Origin server sets cache headers:
Cache-Control: public, max-age=3600
public: Can be cached by CDN
max-age: Cache duration in seconds
Cache Invalidation
Manual: Create invalidation request
Automatic: Wait for TTL expiry
Cost: First 1,000 paths free per month
See: CACHE_INVALIDATION_RULE.md for policy
Origin Protection
CDN protects origin server:
Traffic absorption: CDN handles traffic spikes
DDoS mitigation: Filters malicious traffic
Rate limiting: Prevents origin overload
Benefit: Origin stays responsive
SSL/TLS
Certificate: AWS Certificate Manager
Protocol: TLS 1.2+
Benefit: Encrypted traffic, free certificate
Compression
Gzip: Enabled for text content
Brotli: Enabled for modern browsers
Benefit: Faster downloads, lower bandwidth
Geographic Restrictions
None: Available worldwide
Benefit: Global reach
Monitoring
Metrics:
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Cache hit rate
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Origin requests
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Error rate
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Latency per region
CloudWatch: AWS monitoring service
Cost Optimization
Cache hit rate: Higher = lower costs
Origin requests: Fewer = lower costs
Data transfer: Cached = cheaper
Benefit: CDN reduces infrastructure costs
References
AWS Services
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CloudFront - AWS CDN documentation
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Certificate Manager - SSL certificates
Related Articles
- Multi-Server Architecture - CDN in architecture
Summary
CloudFront CDN improves global performance:
Cached content:
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✅ Static assets (1 year TTL)
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✅ Product pages (1 hour TTL)
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✅ Query pages (5 minutes TTL)
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✅ Articles (24 hours TTL)
Not cached:
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✅ Dynamic search
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✅ User-specific content
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✅ API endpoints
Benefits:
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✅ Lower latency (edge locations)
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✅ Origin protection (traffic absorption)
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✅ DDoS mitigation
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✅ Cost reduction (fewer origin requests)
Features:
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✅ SSL/TLS encryption
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✅ Gzip/Brotli compression
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✅ Global availability
This CDN strategy balances performance, freshness, and cost.