CloudFlare uses Anycast. However, we shift sites around between IPs frequently in order to, for example, isolate a site under DDoS from the rest of our network.
While it may be possible to create a IP-based CDN, my guess is the tradeoffs in terms of not being able to thoroughly defend yourself against attacks would not be worth the few milliseconds saved on the initial DNS lookup.
Comments
CloudFlare uses Anycast. However, we shift sites around between IPs frequently in order to, for example, isolate a site under DDoS from the rest of our network.
While it may be possible to create a IP-based CDN, my guess is the tradeoffs in terms of not being able to thoroughly defend yourself against attacks would not be worth the few milliseconds saved on the initial DNS lookup.