A content delivery network (CDN) replicates content across geographically distributed locations and serves users from a nearby copy. This reduces geographic and last-mile latency while improving availability. section 4.0 section 3.6
CDNs are one form of edge computing. Near-edge locations remain in data centers but sit closer to users than central cloud regions, while far-edge systems operate nearer user networks and devices. The useful distinction is not the label “edge,” but the location and control of the deployed resource. section 3.2.2
CDN deployment involves several practical trade-offs:
- Place content near major user populations to reduce round-trip and last-mile latency. section 3.2.2 section 3.6
- Treat replicated copies as a consistency problem: stronger guarantees require more coordination and can increase latency. section 4.0
- Use geographic redundancy to preserve service when a network path, node, or data center fails. section 4.0
Serving a distant user
A centralized deployment in AWS US-East forces users worldwide to communicate with Virginia. A user in Tokyo can instead reach a nearby edge location, avoiding the full distant round trip. Similarly, a local data center used by Cloudflare can be much closer than the nearest cloud region. section 3.2.2
