A control server receives probe data from a plurality of data centers indicating measured latencies with a first IP address associated with an origin server. The control server sums the measured latencies of a first data center having a lowest measured latency and a second data center. When the sum is below a threshold value, the control server determines the IP address to be an anycast IP address and selects a proper subset of the plurality of data centers as proxying data centers for other data centers in the plurality of data centers. When the sum is not below the threshold value, the control server determines the IP address to not be an anycast IP address and selects the first data center having the lowest measure latencies as the proxying data center for other data centers in the plurality of data centers.