Technically, there is no difference in configuration between the premium and volume zones. The only difference is the number of PoPs used when routing your users. The premium tier uses a smaller number of dynamically predefined and carefully selected datacenters that offer a great price-performance ratio around the globe.
We are constantly monitoring the network for performance and make adjustments as needed in order to provide the best possible speeds. While the locations can change, however, the map below illustrates the general PoPs that you should expect to be used for the volume zones marked in blue.