Internet protocol addressing to uniquely identify clients and destinations across computer networks is provided. Communication between a proxy service and a DNS nameserver is facilitated to permit the DNS nameserver to send a subscriber identifier to the proxy service in response to a DNS request for a flagged domain name. The proxy service selects a unique IP address from a pool of IP addresses assigned to the proxy service. The proxy service associates the selected IP address with the subscriber identifier and optionally, the target domain name of the DNS request. The proxy service provides the unique IP address to the DNS nameserver which returns the unique IP address to the client device for the target domain name. The subscriber can then be authenticated at the proxy service transparently without input from the subscriber or client device based on the unique IP address provided by the client device to the proxy service.