Received August 15, 2021, accepted September 6, 2021, date of publication September 14, 2021, date of current version October 5, 2021. Digital Object Identifier 10.1109/ACCESS.2021.3112926 DNSWeight: Quantifying Country-Wise Importance of Domain Name System DELIANG CHANG 1 , SHANSHAN HAO 1 , ZHOU LI 2 , (Senior Member, IEEE), BAOJUN LIU 3 , AND XING LI 1 1 Department of Electronic Engineering, Tsinghua University, Beijing 100084, China 2 Department of Electrical Engineering and Computer Science, University of California at Irvine, Irvine, CA 92697, USA 3 Institute for Network Sciences and Cyberspace, Tsinghua University, Beijing 100084, China Corresponding author: Xing Li (xing@cernet.edu.cn) ABSTRACT DNS (Domain Name System) is one fundamental Internet infrastructure related to most network activities. As a feasible tool to govern the Internet, DNS’s stability and interoperability will be impacted by the countries’ policies or actions along the path. Especially now that many countries have stricter control over the Internet and even sometimes ‘‘unplug’’ it. But there was no study to quantify the countries’ impact systematically. To fill this research gap, we present DNSWeight. This new data-driven approach utilizes a large-scale DNS dataset and BGP (Border Gateway Protocol) routing information to calculate the country-importance score so that a country’s impact on DNS can be gauged. By applying DNSWeight on large-scale DNS and BGP datasets jointly, our study shows the importance among different countries is divided. A handful of countries show dominant significance to the current DNS ecosystem. Some countries with a history of Internet shutdowns are too influential to be ignored if they choose to break themselves from the Internet. We also examine the impact of IPv6 (IP Version 6) and reveal the ‘‘loop’’ phenomenon that occurs in some DNS queries. In conjunction with our findings, some discussion and suggestions are given. In summary, our study shows that DNS reliability needs to be reconsidered at the country’s level. INDEX TERMS BGP, domain name system, network measurement, network servers. I. INTRODUCTION DNS translates the human-readable domains to network-layer IP addresses. Moreover, as one fundamental Internet infras- tructure, it powers almost all Internet services like email and web. Thus its resilience is often highly concerned. One major threat to DNS resilience is due to its plain-text and connectionless nature: DNS is frequently under attacks like packet manipulation and eavesdropping, which fuels content censorship and access blocking [1]–[3]. We consider the issue from these two perspectives. 1) Who: Country policies and actions influence the DNS ecosystem. DNS is often used as tool by policymakers to censor/manage/monitor the Internet. Countries have the abil- ity, motivation, and action to manipulate or eavesdrop on the system. In recent years, some countries even ‘‘unplug’’ their network from Internet [4]–[6], which may lead to more serious consequences. The associate editor coordinating the review of this manuscript and approving it for publication was Bong Jun David Choi . 2) Where: Countries on the resolution path are equally important. Many previous works only consider DNS servers and the network they are located, e.g., topological distribution of authoritative nameservers. It is insufficient since DNS manipulation is generally enacted using Man-In-The-Middle methods [2]. Until now, there was no consensus on how to quantify the real-world impact of a country on the DNS, though the answer is essential in guiding how the Internet should be advanced. Only a few previous studies looked into the geo-location distribution of root servers and TLD servers [7] and the influence of Autonomous System (AS) [8]. Still, the country-level impact cannot be derived from their result. Therefore, the main effort of this work is to collect relevant data and develop a new methodology to assess country-wise importance on DNS, under the consideration of path information. Achieving such a goal is non-trivial, however. It is impos- sible to ‘‘turn off’’ and ‘‘turn on’’ a specific country net and learn its precise real-world impact. Although researchers 133240 This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License. For more information, see https://creativecommons.org/licenses/by-nc-nd/4.0/ VOLUME 9, 2021