NTP Associations
An NTP association can be one of the following:
- A peer association: The device can either synchronize to another device or allow another device to synchronize to it.
- A server association: The device synchronizes to a server.
You need to configure only one end of an association. The other device can automatically establish the association.
All users should ensure that their software NEVER queries a server more frequently than once every 4 seconds. Systems that exceed this rate will be refused service. In extreme cases, systems that exceed this limit may be considered as attempting a denial-of-service attack.
(NTP) is a UDP-based service. NTP servers use well-known port UDP/123 to talk to each other and to NTP clients.
CovertHart Networks
| Hostname | IPv4 Address | IPv6 Address | Description |
|---|---|---|---|
| ntp1.coverthart.net | 209.46.0.36 | 2602:2ac:2ac:1000::36 | Miami, FL |
| ntp2.coverthart.net | 159.203.179.95 | 2604:a880:400:d0::23f2:6001 | New York, NY |
NIST – National Institute of Standards and Technology
| Hostname | IPv4 Address | IPv6 Address | Location |
|---|---|---|---|
| time-d-g.nist.gov | 129.6.15.27 | 2610:20:6f15:15::27 | NIST, Gaithersburg, Maryland |
| time-a-g.nist.gov | 129.6.15.28 | — | NIST, Gaithersburg, Maryland |
| time-b-g.nist.gov | 129.6.15.29 | — | NIST, Gaithersburg, Maryland |
| time-c-g.nist.gov | 129.6.15.30 | — | NIST, Gaithersburg, Maryland |
| time-a-b.nist.gov | 132.163.96.1 | — | NIST, Boulder, Colorado |
| time-b-b.nist.gov | 132.163.96.2 | — | NIST, Boulder, Colorado |
| time-c-b.nist.gov | 132.163.96.3 | — | NIST, Boulder, Colorado |
| time-d-b.nist.gov | 132.163.96.4 | 2610:20:6f96:96::4 | NIST, Boulder, Colorado |
| time-a-wwv.nist.gov | 132.163.97.1 | — | WWV, Fort Collins, Colorado |
| time-b-wwv.nist.gov | 132.163.97.2 | — | WWV, Fort Collins, Colorado |
| time-c-wwv.nist.gov | 132.163.97.3 | — | WWV, Fort Collins, Colorado |
| time-d-wwv.nist.gov | 132.163.97.4 | 2610:20:6f97:97::4 | WWV, Fort Collins, Colorado |
USNO – United States Naval Observatory
| Server Name | IPv4 Address | IPv6 Address | Description / Location |
|---|---|---|---|
| tick.usno.navy.mil | 192.5.41.40 | — | Washington, DC |
| tock.usno.navy.mil | 192.5.41.41 | — | Washington, DC |
| ntp2.usno.navy.mil | 192.5.41.209 | — | Washington, DC |
| tick.usnogps.navy.mil | 204.34.198.40 | — | Colorado Springs, CO |
| tock.usnogps.navy.mil | 204.34.198.41 | — | Colorado Springs, CO |
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