Why UTC Alone Doesn't Guarantee Clock Agreement: Five Myths That Break Deploys

A developer article argues that developers often assume UTC timestamps mean servers agree on the time, which is not guaranteed since a shared format does not synchronize clocks. It identifies five common misconceptions, including treating time agreement as exact rather than within a tolerance and using wall-clock time to measure elapsed intervals. The piece explains that wall clocks can be corrected or jump, while monotonic clocks may not advance during suspend, so the right clock depends on the question being asked. It also notes that cron is not a catch-up scheduler and can be affected by timezone settings, clock corrections, and unescaped percent signs. The author provides diagnostic methods for developers to measure drift and clock behavior on their own systems.