Variable DNS responses based on client identity

An address resolver such as a DNS service may use the identity of a requesting client device to determine a response of a network address for a hostname in a request. A requesting client device may transmit a hardware or user identifier to an address resolving server in order to authenticate the client. The server may determine if the requesting client is authorized to have access to the requested hostname, and respond with the network address when the client is authorized. The address resolver may be used to limit access for users to various devices or hosts across a network and in some cases may track which users are accessing which hosts.