1. A method to monitor media exposure, the method comprising: receiving, at a first internet domain, a first request from a client device, the first request indicative of access to media at the client device, and the first request including identifying information identifying the media; generating a substitute value at the first internet domain after receiving the first request at the first internet domain, the substitute value corresponding to the identifying information and obfuscating an identity of the media; determining if the client device is known; if the client device is not known, sending, from the first internet domain to the client device, a response including the substitute value in place of the identifying information, the response to instruct the client device to send a second request to a second internet domain, the substitute value to be included in the second request to the second internet domain to hide the identity of the media from the second internet domain; and if the client device is known, logging an impression of the media without sending the second request to the second internet domain.