Dual-End Measurement Framework for Public Resolvers

In recent years, the concentration risk of the Internet has intensified, with traffic being concentrated in the hands of a few service providers. However, existing research focuses on the client-side perspective and lacks a centralized measurement of the public resolver in terms of operation strategies and software functionality implementation. Therefore, we propose a dual-end measurement framework to measure the public resolver from both the client and authoritative perspectives, stably matching the active nodes of the public resolver pool with their providers, and using probes to evaluate the diversity of its functionality implementation and configuration schemes. The study analyzed the operation plans of different suppliers and revealed the regional nature of the public resolver service scope, enabling the localization of specific resolver instances, thereby achieving a concentration assessment for specific suppliers. In actual measurements from the perspectives of 5 countries and regions using 14 probes on 4 large public resolvers and 7 regional resolvers, we found that although anycast provides geographical redundancy, the software implementation logic of the public resolver cluster in a single region tends to be somewhat homogeneous. The characteristic entropy of Google in five regions was 1.435, while in the Silicon Valley region of the United States, there was only one software implementation.