I believe in reality it's a bit more complicated CDNs do not choose datacenters for users based on a geographic distance. The number one metric is latency but

I believe in reality it's a bit more complicated CDNs do not choose datacenters for users based on a geographic distance. The number one metric is latency but latency != physical distance. Second metric is optimizations of price of data transfer between peers and IXPs which results in very dynamic routing rules. Then consider also network/software hickups/maintanance and distribution of datacenters' load...