In rDNS We Trust: Revisiting a Common Data-Source's Reliability

Reverse DNS (rDNS) is regularly used as a data source in Internet measurement research. However, existing work is polarized on its reliability, and new techniques to collect active IPv6 datasets have not yet been sufficiently evaluated. In this paper, we investigate active and passive data collection and practical use aspects of rDNS datasets. We observe that the share of non-authoritatively answerable IPv4 rDNS queries reduced since earlier studies and IPv6 rDNS has less non-authoritatively answerable queries than IPv4 rDNS. Furthermore, we compare passively collected datasets with actively collected ones, and we show that they enable observing the same effects in rDNS data. While highlighting opportunities for future research, we find no immediate challenges to the use of rDNS as active and passive data-source for Internet measurement research