Dear RSSAC Caucus, On behalf of the caucus work party on Root Zone TTLs, attached please find for your review the draft RSSAC Report on Root zone TTLs. The work party is chaired by Duane Wessels, work party members include Joe Abley, Jaap Akkerhuis, John Bond, Brian Dickson, Shumon Huque, Warren Kumari, Duane Wessels (work party leader) and Matthew Thomas (invited expert). Staff support are: Steve Sheng, Barbara Roseman and Kathy Schnitt. Root zone TTLs have not changed since 1999. In this report, the RSSAC caucus studies the extent to which the current root zone TTLs are still appropriate for today¹s internet environment. The report contains a number of findings and recommendations through four sets of empirical analyses. The work party chair invites you to give this report a careful review. One thing the chair wish to highlight is that the work party discovered two potential problems related to the interaction between the SOA Expire value and the root zone¹s signature validity period. It also identified several mitigation options, and conducted a preliminary analysis of these options. However, the work party has yet to reach a conclusion to recommend which measure to take. It would be good to hear some feedback from the Caucus. Short of more definitive feedback from the Caucus, the work party will recommend further consultation in this area. The work party chair requests you provide your review by close of business (anywhere around the world) 15 June 2015, if possible. This will allow the work party time to discuss and finalize the document in time for RSSAC consideration in Buenos Aires. All the best, Steve