Ecco un elenco di Internet Time Servers per il protocollo SNTP (Simple Time Network Protocol): non esiste solo time.nist.gov o time.windows.com!
NAME, IP ADDRESS, LOCATION
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
time-nw.nist.gov 131.107.1.10 Microsoft, Redmond, Washington
nist1.datum.com 63.149.208.50 Datum, San Jose, California
nist1.dc.glassey.com 216.200.93.8 Abovenet, Virginia
nist1.ny.glassey.com 208.184.49.9 Abovenet, New York City
nist1.sj.glassey.com 207.126.103.204 Abovenet, San Jose, California
nist1.aol-ca.truetime.com 207.200.81.113 True Time, Sunnyvale, California
nist1.aol-va.truetime.com 205.188.185.33 True Time, Virginia
E qualche utile link..
http://support.ntp.org/bin/view/Servers/WebHome#Browsing_the_Lists