Methods, apparatus and systems for processing digital content service requests from user devices in a user network are disclosed. The method, performed by a control device, comprises receiving policy indications in respect of the user devices indicating desired control policies to be implemented in respect of the user devices, and associating user device source identifiers with the user devices indicating a network location to which responses should be directed, the user device source identifier associated with a particular user device depending on the policy indication for that user device. On receiving digital content service requests containing indications of domain names associated with content providers from which digital content is desired, the control device submits server location requests to a domain name system server comprising (i) the domain name from the digital content service request and (ii) the user device source identifier for the user device in question.