What time is it - managing time in the internet.

In this paper, we report on our investigation of how current local time is reported accurately by devices connected to the internet. We describe the basic mechanisms for time management and focus on a critical but unstudied aspect of managing time on connected devices: the time zone database (TZDB). Our longitudinal analysis of the TZDB highlights how internet time has been managed by a loose confederation of contributors over the past 25 years. We drill down on details of the update process, update types and frequency, and anomalies related to TZDB updates. We find that 76% of TZDB updates include changes to the Daylight Saving Time (DST) rules, indicating that DST has a significant influence on internet-based time keeping. We also find that about 20% of updates were published within 15 days or less from the date of effect, indicating the potential for instability in the system. We also consider the security aspects of time management and identify potential vulnerabilities. We conclude with a set of proposals for enhancing TZDB management and reducing vulnerabilities in the system.