1. A computer-implemented method for request routing comprising: obtaining a DNS query from a client computing device, wherein the DNS query corresponds to a requested resource associated with a resource identifier, the requested resource provided by a content provider to a service provider; identifying one or more sets of POPs associated with the service provider based on prioritization information selected by the content provider; determining whether one or more POPs in the identified POPs can service additional content requests based on availability information associated with the one or more POPs; and transmitting information responsive to the DNS query based on the determination that one or more POPs have capacity.