Web Tracking Cartography with DNS Records

Web tracking plays a crucial role in the Web ecosystem. It relies on third-party tracking domains collecting user information for various applications such as advertisement and analytics. With the massive growth of the Internet, understanding tracking and its geographical roots is of strategic importance. The goal of this paper is to propose a thorough investigation of web tracking inside China taking advantage of a large dataset (10 ¹¹ records) containing two days of full DNS access from a major ISP providing both mobile and landline ADSL. Our results show that a power law applies on the traffic of both sites and trackers with a handful of trackers, 26, representing 90% of tracking activity. We then show that although most first-party sites accessed from China are owned by Chinese corporations, large proportion of trackers belong to US ones. This raises concerns about the analytics industry in China, and more generally shed new lights on the international data flows, the interdependency of the main actors, and the complexity of the threats for both people and states.