CDNs route users to optimal edge servers:
DNS-based routing:
- CDN's DNS returns different IPs based on user location
- Simple but limited precision (DNS resolver location, not user)
Anycast routing:
- Same IP announced from multiple locations
- Network routing finds closest server
- Used by Cloudflare, Google
HTTP redirect:
- Initial request redirected to optimal server
- Adds latency but most accurate
Factors considered:
- Geographic distance
- Server load
- Network conditions
- Content availability