Using NTP to Sync Your Clock on Linux

Synchronize Time on Installed Linux Operating Systems

1. On the Linux machine, log in as root.
2. Run the ntpdate -u <ntpserver> command to update the machine clock. For example, ntpdate -u ntp-time. ...
3. Open the /etc/ntp. conf file and add the NTP servers used in your environment. ...
4. Run the service ntpd start command to start the NTP service and implement you configuration changes.

1. How does NTP synchronize time in Linux?
2. How do I know if NTP is synchronized Linux?
3. Does NTP sync time zone?
4. How do I set NTP synchronized yes?
5. Where does NTP set time from?
6. What is an acceptable NTP offset?
7. How can I tell which NTP server my client is synchronized with?
8. How do I test NTP connection?
9. How do I check if my NTP server is working?
10. How long does NTP sync take?
11. How does NTP server sync time?
12. How often does NTP sync Windows?

How does NTP synchronize time in Linux?

The most common method to sync system time over a network in Linux desktops or servers is by executing the ntpdate command which can set your system time from an NTP time server. In this case, the ntpd daemon must be stopped on the machine where the ntpdate command is issued.

How do I know if NTP is synchronized Linux?

To verify that your NTP configuration is working properly, run the following:

1. Use the ntpstat command to view the status of the NTP service on the instance. [ec2-user ~]$ ntpstat. ...
2. (Optional) You can use the ntpq -p command to see a list of peers known to the NTP server and a summary of their state.

Does NTP sync time zone?

NTP does not regconize time zones, instead it manages all time informations based on UTC. In general the handling of time zones is a job of a computer's operating system. ... Example: If you configure Windows to use your local time zone, the system clock continues with using UTC time.

How do I set NTP synchronized yes?

Network time on: yes means that timesyncd is enabled, and NTP synchronized: yes indicates that the time has been successfully synced. If timesyncd isn't enabled, turn it on with timedatectl: sudo timedatectl set-ntp on.

Where does NTP set time from?

ntpdate sets the local date and time by polling the Network Time Protocol (NTP) server(s) given as the server arguments to determine the correct time. It must be run as root on the local host.

What is an acceptable NTP offset?

The maximum slew rate possible is limited to 500 parts-per-million (PPM) by the Unix kernel. As a result, the clock can take 2000s for each second the clock is outside the acceptable range. According to the manual page ntpd won't work if your clock is more then 1000 seconds off.

How can I tell which NTP server my client is synchronized with?

The ntpstat command will report the synchronisation state of the NTP daemon running on the local machine.
...
exit status of ntpstat command

1. If exit status 0 – Clock is synchronised.
2. exit status 1 – Clock is not synchronised.
3. exit status 2 – If clock state is indeterminant, for example if ntpd is not contactable.

How do I test NTP connection?

1. Click Start. Type "cmd" into the text box and press "Enter." The command utility will appear.
2. Type the following: NET TIME \YourServer /SET /YES. ...
3. Alter the time on the server to any time and make a note of it.
4. Check the time on your client computer.

How do I check if my NTP server is working?

To verify the NTP server list:

1. Click on the Windows button.
2. In the "Search programs and files" box, type cmd and press Enter.
3. If necessary, select cmd from the list of search results.
4. In the command prompt window, enter w32tm /query /peers.
5. Check that an entry is shown for each of the servers listed above.

How long does NTP sync take?

The packet exchange takes place until a NTP server is accepted as a synchronization source, which take about five minutes. The NTP daemon tries to adjust the clock in small steps and will continue until the client gets the accurate time.

How does NTP server sync time?

NTP is intended to synchronize all participating computers to within a few milliseconds of Coordinated Universal Time (UTC). It uses the intersection algorithm, a modified version of Marzullo's algorithm, to select accurate time servers and is designed to mitigate the effects of variable network latency.

How often does NTP sync Windows?

The date time of your PC (specific for windows) sync with one of the listed NTP server. This time sync happens every 7 days and with time.windows.com by default. You can also manually sync or update your time.