This was an NTP 0 server right? What is the actual failback mechanism when that level of NTP server fails?

This is some level of eldritch magic that I am aware of, but not familiar with but am interested in learning.

There's two other sites for the time.nist.gov service so it'll be okay.

Probably more interesting is how you get a tier 0 site back in sync - NIST rents out these cyberpunk looking units you can use to get your local frequency standards up to scratch for ~$700/month https://www.nist.gov/programs-projects/frequency-measurement...

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3eb7988a1663 2 days ago | parent | next [-]

Considering how many servers are in existence, probably the exact same procedure for starting a brand new one?

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wpm 2 days ago | parent | prev | next [-]

I must have one of those units oh my god

	▲	mh- 2 days ago \| parent \| next [-]
		Someone needs to sell replicas (forgive the pun) of these.
	▲	wat10000 2 days ago \| parent \| prev [-]
		It's like a toaster oven, but it toasts time.

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lovich 2 days ago | parent | prev [-]

What happens in the event all the sites for time.nist.gov go down? is it included in the spec?

Also thank you for that link, this is exactly the kind of esoteric knowledge that I enjoy learning about

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sdrmill 2 days ago | parent [-]

Most high-availability networks use pool.ntp.org or vendor-specific pools (e.g., time.cloudflare.com, time.google.com, time.windows.com). These systems would automatically switch to a surviving peer in the pool.

Many data centers and telecom hubs use local GPS/GNSS-disciplined oscillators or atomic clocks and wouldn’t be affected.

Most laptops, smartphones, tablets, etc. would be accurate enough for days before drift affected things for the most part.

Kerberos requires clocks to be typically within 5 minutes to prevent replay attacks, so they’d probably be ok.

Sysadmins would need to update hardcoded NTP configurations to point to secondary servers.

If timestamps were REALLY off, TLS certificates might fail, but that’s highly unlikely.

Databases could be corrupted due to failure of transaction ordering.

Financial exchanges are often legally required to use time traceable to a national standard like UTC(NIST). A total failure of the NIST distribution layer could potentially trigger a suspension of electronic trading to maintain audit trail integrity.

Modern power grids use Synchrophasors that require microsecond-level precision for frequency monitoring. Losing the NIST reference would degrade the grid's ability to respond to load fluctuations, increasing the risk of cascading outages.

	▲	neomantra 2 days ago \| parent [-]
		Great list! Just double-checked the CAT timekeeping requirements [1] and the requirement is NIST sync. So a subset of all UTC. You don’t need to actually sync to NIST. I think most people PTP/PPS to a GPS-connected Grandmaster with high quality crystals. But one must report deviations from NIST time, so CAT Reporters must track it. I think you are right — if there is no NIST time signal then there is no properly auditable trading and thus no trading. MFID has similar stuff but I am unfamiliar. One of my favorite nerd possessions is my hand-signed letter from Judah Levine with my NIST Authenticated NTP key. [1] https://www.finra.org/rules-guidance/rulebooks/finra-rules/6...

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lambdaone 2 days ago | parent | prev [-]

There are lots of Stratum 0 servers out there; basically anything with an atomic clock will do. They all count seconds independently from one another, all slowly diverging over time, with offset intervals being measured by mutual synchronization using a number of means (how is this done is interesting all by itself). Some atomic clocks are more accurate than others, and an ensemble of these is typically regarded as 'the' master clock.

To quote the ITU: "UTC is based on about 450 atomic clocks, which are maintained in 85 national time laboratories around the world." https://www.itu.int/hub/2023/07/coordinated-universal-time-a...

Beyond this, as other commenters have said, anyone who is really dependent on having exact time (such as telcos, broadcasters, and those running global synchronized databases) should have their own atomic clock fleets. There are thousands and thousands of atomic clocks in these fleets worldwide. Moreover, GPS time, used by many to act as their time reference, is distributed by yet other means.

Nothing bad will happen, except to those who have deliberately made these specific Stratum 0 clocks their only reference time. Anyone who has either left their computer at its factory settings or has set up their NTP configuration in accordance to recommended settings will be unaffected by this.