Here is a list of alternative time servers for use with AtomTime.

URL IP address Site name
time-a.nist.gov  129.6.15.28  NIST, Gaithersburg, Maryland
time-b.nist.gov 129.6.15.29  NIST, Gaithersburg, Maryland
time-a.timefreq.bldrdoc.gov 132.163.4.101 NIST, Boulder, Colorado
time-b.timefreq.bldrdoc.gov  132.163.4.102 NIST, Boulder, Colorado
time-c.timefreq.bldrdoc.gov 132.163.4.103 NIST, Boulder, Colorado
utcnist.colorado.edu 128.138.140.44 University of Colorado, Boulder
time.nist.gov 192.43.244.18  NCAR, Boulder, Colorado
nist1.datum.com 209.0.72.7  Datum, San Jose, California
nist1.nyc.certifiedtime.com  208.184.49.129 Abovnet, New York City
nist1.sjc.certifiedtime.com  207.126.103.202 Abovnet, San Jose, California