Managing request routing information utilizing performance information

Systems and methods for managing requesting routing functionality associated with resource requests for one or more resources associated with a content provider are provided. The request routing functionality can correspond to the processing of domain name service ("DNS") requests for resources by computing devices and the resolution of the DNS requests by the identification of a network address of a computing device that will provide the requested resources. Based on the processing resource requests initiated by a client computing device, a CDN service provider can obtain performance information from client computing devices and correlate the performance information into a prioritized list for classes of client computing devices. The prioritized list can be utilized in resolving subsequent DNS queries.