A content distribution system has a DNS server which is configured to provide DNS responses in response to DNS requests, and a device which interconnects between a client and the DNS server. The device includes an interface which communicates with the client, and a controller coupled to the interface. The controller can intercept a first DNS request en route from the client to the DNS server, and provide a second DNS request to the DNS server through the interface in response to interception of the first DNS request. The second DNS request selectively includes a client identifier which identifies the client, and not including the client identifier which identifies the client, based on a selection decision. The controller can further convey a DNS response from the DNS server to the client through the interface. The DNS response includes a content server identifier which identifies a content server.