What is Amazon CloudFront?
Why Interviewers Ask This
Interviewers use this question to quickly assess whether a candidate has the foundational knowledge required for AWS / Cloud Computing development. It reveals whether you understand the building blocks that more complex concepts rely on.
Answer
Amazon CloudFront is AWS's Content Delivery Network (CDN) that speeds up distribution of static and dynamic web content — HTML, CSS, JavaScript, images, videos, APIs — by serving from edge locations closest to users. How it works: user requests content → CloudFront routes to nearest edge location (450+ globally) → if cached (cache hit), serves immediately → if not (cache miss), fetches from origin, caches, and serves. Origins: S3 bucket (ideal for static content), ALB/EC2, API Gateway, any HTTP server. Multiple origins with failover. Key features: (1) HTTPS/SSL: free TLS certificates via ACM (AWS Certificate Manager); (2) Custom domain: use your domain with CNAME; (3) Cache behaviors: per path pattern cache settings (e.g., /api/* bypass cache, /static/* cache for 1 year); (4) Cache invalidation: aws cloudfront create-invalidation --paths "/index.html" "/*"; (5) Lambda@Edge / CloudFront Functions: run code at edge locations — URL rewrites, auth, request/response manipulation; (6) Origin Access Control (OAC): restrict S3 access to CloudFront only (S3 not public); (7) WAF integration: block malicious traffic at edge; (8) Field-Level Encryption: encrypt sensitive data at edge; (9) Real-Time Logs: stream access logs to Kinesis. Pricing: data transfer from edge + HTTP request count. No charge for S3 origin data transfer to CloudFront within same region. Free tier: 1TB data transfer + 10M requests/month.
Common Mistake
Many candidates answer correctly but can't explain the 'why'. Always be prepared to justify your answer with a concrete example or use case from your AWS / Cloud Computing experience.