A content delivery system includes an analyzer module, a content request data collection module, and a domain name server. The collection module receives request sent to a tracking address, collects information about the request, and provides the information to the analyzer. The server receives an address request from a local domain name server associated with an autonomous system for the cache server address, provides the tracking address to the local server because the local server is associated with the second autonomous system, collects address request information about the address, and provides the address request information to the analyzer module. The analyzer module receives the address request and content request information, and determines information about clients served by the autonomous system based on the address request and content request information.