[ntp:questions] Failure of NIST Time Servers

jlevine jlevine at boulder.nist.gov
Fri May 27 20:16:17 UTC 2011

The primary and backup ACTS servers that are used to synchronize the
Internet time servers to the atomic clock ensemble in Boulder failed
on Wednesday 24 May at about 1900 UTC (1300 MDT). The failure
11 of the 35 NIST Internet time servers, and the time transmitted by
the affected servers was wrong by up to 680 seconds. In most cases,
the incorrect time was accompanied by the unhealthy indicator, but
of the systems transmitted the wrong time without this indication. The
other 24 servers were not affected. In some cases, one of the physical
servers at a site was affected while the others were not, so that
repeated requests to the public site address resulted in time messages
that differed by up to 680 seconds.

The ACTS servers have been fully repaired as of 27 May, 1800 UTC (1200
and all of the servers should be resynchronized within a few hours.
may be a transient error of up to 10 milliseconds during this period.

I apologize for this failure, and I regret the problems and
that have resulted.

Judah Levine
jlevine at boulder.nist.gov

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