How accurate is ntpd?
Table of Contents
How accurate is ntpd?
NTP can usually maintain time to within tens of milliseconds over the public Internet, and can achieve better than one millisecond accuracy in local area networks under ideal conditions. Asymmetric routes and network congestion can cause errors of 100 ms or more.
How long does ntpd take to sync?
Usually it takes about five minutes (five good samples) until a NTP server is accepted as synchronization source. Interestingly, this is also true for local reference clocks that have no delay at all by definition.
How does NTPD work?
NTP uses Coordinated Universal Time (UTC) to synchronize computer clock times with extreme precision. It offers greater accuracy on smaller networks — down to 1 millisecond in a local area network (LAN) and within tens of milliseconds over the internet. NTP does not account for time zones.
Is GPS time more accurate than NTP?
GPS accuracy is ~ 1 microsecond. NTP accuracy is ~ 100 milliseconds. GPS is more accurate than NTP and has less latency compared to NTP. clear sky, and after satellites are locked, the GPS master clock will send a signal every second to the slave clocks.
Does chrony use port 123?
This option allows the UDP port on which the server understands NTP requests to be specified. For normal servers this option should not be required (the default is 123, the standard NTP port).
How do I know if my chrony is synchronized?
To check if chrony is synchronized, use the tracking, sources, and sourcestats commands. Run the chronyc tracking command to check chrony tracking. Alternatively you could run chronyc to display a chronyc> prompt, and then run the tracking command from the chronyc> prompt.
Does GPS use NTP?
The GPS receiver provides the NTP service with time stamps to accurately synchronize an internal clock.
Where is ntpd Linux?
Linux OS Service ‘ntpd’
- Service Name.
- The ntpd program operates by exchanging messages through UDP port 123 with one or more configured servers at designated poll intervals.
- Note: this service is needed even for NTP clients.
- # /sbin/service ntpd usage: /etc/init.d/ntpd {start|stop|restart|condrestart|status}
What does ntpd GQ do?
The -gq tells the ntp daemon to correct the time regardless of the offset (g) and exit immediately (q) after setting the time.
