It sounds like GPS, and thus a GPS-based stratum 1 server, uses these time servers, but they were successfully failed over:

> Jeff finished off the email mentioning the US GPS system failed over successfully to the WWV-Ft. Collins campus. So again, for almost everyone, there was zero issue, and the redundancy designed into the system worked like it's supposed to.

So failures in these systems are potentially correlated.

The author mentions another solution. Apparently he runs his own atomic clock. I didn’t know this was a thing an individual could do.

> But even with multiple time sources, some places need more. I have two Rubidium atomic clocks in my studio, including the one inside a fancy GPS Disciplined Oscillator (GPSDO). That's good for holdover. Even if someone were jamming my signal, or my GPS antenna broke, I could keep my time accurate to nanoseconds for a while, and milliseconds for months. That'd be good enough for me.

Be aware that there are members of the NTP pool with less-than-honorable intentions and you don't get to pick-and-choose. Yes, they all should provide the time, but they also get your IP address.

For example: unlike the IPv4 space, the IPv6 space is too big too scan, so a number of "researchers" (if you want to call them that) put v6-capable NTP servers in the NTP pool to gather information about active v6 blocks to scan/target.