Network performance monitoring in a content delivery service

A method for Internet content delivery, comprising:

• establishing a content delivery network at network locations, the content delivery network comprising a plurality of content servers for serving content resources, wherein the plurality of content servers includes a plurality of subsets of content servers, each subset located at one of a plurality of Internet data centers;
• for each Internet Protocol (IP) address block from which requests for content resources are expected to be received, generating a candidate list of Internet data centers to be used to service the requests for content resources, wherein the candidate list of Internet data centers is generated using (i) geographic information from one or more Internet registry databases identifying a geographic location of the IP address block, (ii) BGP route information collected from BGP peers participating in BGP (BGP) sessions, (iii) autonomous system (AS) information, and (iv) data collected from one or more network performance metric tests;
• and;
• for the IP address block, selecting at least one of the Internet data centers from the candidate list to be used to service the requests for content resources, wherein the selected Internet data center is written into a network map, and wherein the selecting step is carried out concurrently for each IP address block from which requests for content resources are expected to be received such that the network map comprises the selected Internet data center for each IP address block;
• providing the network map to a domain name service (DNS) associated with the content delivery network;
• and
• in response to a DNS query received at the domain name service associated with the content delivery network, using the network map to identify one of the Internet data centers from the candidate list to be used to service a request for a content resource.