From the ISC Diary:
A few people have written in within the past 18 hours about their NTP server/clients getting set to the year 2000. The cause of this behavior is that an NTP server at the US Naval Observatory (pretty much the authoritative time source in the US) was rebooted and somehow reverted to the year 2000. This, then, [propagated] out for a limited time and downstream time sources also got this value. It’s a transient problem and should already be rectified. Not much really to report except an error at the top of the food chain causing problems to the layers below. If you have a problem, just fix the year or resync your NTP server.
Doesn’t look like this impacted me at all, if it did logs and graphs would look funny. This however is quite freaky. Curious if this had any bigger impacts like financial transactions. You would think they would have some sort of check for strange NTP updates as a clock drift of 12 years is out of the ordinary, but anything is possible.
I’d also be curious to know how that server reverted to the year 2000. Perhaps it was something as simple as the CMOS battery died.