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 |