CloudFront — CDN & Edge

CloudFront = CDN (Content Delivery Network)

• Caches content at 300+ edge locations worldwide
• Users served from NEAREST edge → lower latency
• Sits in front of: S3, ALB, EC2, Lambda, API Gateway (the “origin”)

Without CloudFront: Jakarta user → us-east-1 → 200ms+
With CloudFront:    Jakarta user → Singapore edge → 30ms

Key terms

• Edge location = small cache (content copies, TTL-controlled)
• Regional edge cache = bigger cache between edge and origin
• Origin = source of truth (S3 bucket, ALB, custom server)
• TTL = cache lifetime (configurable)
• Lambda@Edge = run code at edge locations (A/B tests, auth, rewrites)
• Integrates: Shield (DDoS at edge), WAF (web attacks at edge), S3 static sites

CloudTrail vs CloudFront (never confuse)

CloudTRAIL = TRAIL of actions — audit log: "who did what, when, from where"
CloudFRONT = FRONT of your app — CDN: "deliver content fast from nearest edge"

Trail = behind you (history of API calls)
Front = in front of you (content delivery)

Exam facts

• “improve latency for global users” → CloudFront
• “cache static content at edge” → CloudFront
• S3 (origin) + CloudFront (edge) = static website pattern
• CloudTrail = API audit (see management-services page)

Related

• [[aws/index]]
• [[aws/management-services/index]]
• [[aws/storage-types/index]]