Latency analysis of JP and Root DNS servers from packet capture data

IP anycast is widely used for root and TLD DNS servers to reduce latency. DNS operators need to perform measurements to understand and improve their service quality. Although it is vital to measure the effect of IP anycast, the measurement requires enough worldwide measurement points to send queries. In this paper, we try a more manageable approach, i.e., analyzing the existing capture data to reveal the response delays between resolvers and authoritative DNS servers. There are two packet capture datasets, the DITL and JP datasets. The DITL dataset is collected by Root server operators and maintained by DNS-OARC. The JP dataset is collected for JP TLD operations. Specifically, we extracted communication delay information from TCP session data in these datasets.Our analysis that uses multiple datasets, i.e., DITL and JP datasets, reveals: 1) Approximately 30% of IPv4 addresses seen at the M-Root & JP DNS server have RTT information and come from over 200 countries. 2) JP DNS servers offer RTT of less than 20ms for 80% of queries from Japan, and RTT of less than 100ms for 80% of queries from outside of Japan. 3) The newly installed M-root Brisbane node offers shorter RTTs in Australia.