Regional variation in Chinese internet filtering

Internet filtering in China is a pervasive and well-reported phenomenon and, as arguably the most extensive filtering regime in the world today, has been studied by a number of authors. Existing studies, however, have considered both the filtering infrastructure and the nation itself as largely homogeneous in this respect. This article investigates variation in filtering across China through direct access to internet services across the country. This is achieved through use of the Domain Name Service (DNS), which provides a mapping between human-readable names and machine-routable internet addresses, and is thus a critical component of internet-based communications. Manipulation of DNS is a common mechanism used by states and institutions to hamper access to internet services that have been deemed undesirable. Our experiments support the hypothesis that, despite typically being considered a monolithic entity, the Chinese filtering approach is better understood as a decentralized and semi-privatized operation in which low-level filtering decisions are left to local authorities and organizations. This article provides a first step in understanding how filtering affects populations at a fine-grained level, and moves towards a more subtle understanding of internet filtering than those based on the broad criterion of nationality. The techniques employed in this work, while here applied to geographic criteria, provide an approach by which filtering can be analysed according to a range of social, economic and political factors in order to more fully understand the role that internet filtering plays in China, and around the world