Researchers and practitioners often face the issue of having to attribute anIP address to an organization. For current data this is comparably easy, usingservices like whois or other databases. Similarly, for historic data, severalentities like the RIPE NCC provide websites that provide access to historicrecords. For large-scale network measurement work, though, researchers oftenhave to attribute millions of addresses. For current data, Team Cymru providesa bulk whois service which allows bulk address attribution. However, at thetime of writing, there is no service available that allows historic bulkattribution of IP addresses. Hence, in this paper, we introduce and evaluateour `Back-to-the-Future whois' service, allowing historic bulk attribution ofIP addresses on a daily granularity based on CAIDA Routeviews aggregates. Weprovide this service to the community for free, and also share ourimplementation so researchers can run instances themselves.<br
