Characterization of Collaborative Resolution in Recursive DNS Resolvers

Abstract

Recursive resolvers in the Domain Name System play a critical role in not only DNS’ primary function of mapping hostnames to IP addresses but also in the load balancing and performance of many Internet systems. Prior art has observed the existence of complex recursive resolver structures where multiple recursive resolvers collaborate in a “pool”. Yet, we know little about the structure and behavior of pools. In this paper, we present a characterization and classification of resolver pools. We observe that pools are frequently disperse in IP space, and some are even disperse geographically. Many pools include dual-stack resolvers and we identify methods for associating the IPv4 and IPv6 addresses. Further, the pools exhibit a wide range of behaviors from uniformly balancing load among the resolvers within the pool to proportional distributions per resolver.