A few months ago, an engineer in a data center in Norway encountered some perplexing errors that caused a Windows server to suddenly reset its system clock to 55 days in the future. The engineer relied on the server to maintain a routing table that tracked cell phone numbers in real time as they were being moved from one carrier to the other. A jump of eight weeks had dire consequences because it caused numbers that had yet to be transferred to be listed as having already been moved and numbers that had already been transferred to be reported as pending.

“With these updated routing tables, a lot of people were unable to make calls, as we didn’t have a correct state!” the engineer, who asked to be identified only by his first name, Simen, wrote in an email. “We would route incoming and outgoing calls to the wrong operators! This meant, e.g., children could not reach their parents and vice versa.”

A show-stopping issue

Simen had experienced a similar error last August when a machine running Windows Server 2019 reset its clock to January 2023 and then changed it back a short time later. Troubleshooting the cause of that mysterious reset was hampered because the engineers didn’t discover it until after event logs had been purged. The newer jump of 55 days, on a machine running Windows Server 2016, prompted him to once again search for a cause, and this time, he found it.