A cartography of web tracking using DNS records

International audienceWeb tracking plays a crucial role in the Web ecosystem. It relies on third-party tracking actors collecting user information that are used for various applications such as advertisement and analytics, etc. With the massive growth of the Internet, understanding the geography of tracking 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 (records) containing two days of full DNS access from a major ISP providing both mobile and landline ADSL. Our results show that a strong Pareto principle applies on the traffic toward trackers, with only 26 trackers, 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 advertisement 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