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FileZilla is spending way too much time copying files that are already there because the clocks on my systems vary too much.

I want to set them all to the Master Clock (like WWV)

According to the NIST page, the National Bureau of Standards suggests using time.nist.gov as the address that will reach a working system among all of the Stratum-1 and 2 servers available:

NIST Internet Time Servers

Obviously, Ubuntu is using time server pools, like Microsoft does, which are many hops away from the master clock source.

My question is in the title: How do I set Ubuntu to use the primary time server time.nist.gov?

marked as duplicate by muru, Eric Carvalho, Charles Green, Zanna, Videonauth Nov 5 '17 at 0:53

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.


The previous answer is quite good but it describes the ntp package which isn't installed by default. Nowadays Ubuntu uses systemd which has a piece of code for time synchronization. You need to edit /etc/systemd/timesyncd.conf file and change the line #NTP= to NTP=time.nist.gov. After that you need to apply the changes:

$ sudo systemctl restart systemd-timesyncd

And check the status:

$ systemctl status systemd-timesyncd
    systemd[1]: Starting Network Time Synchronization...
    systemd[1]: Started Network Time Synchronization.
    systemd-timesyncd[30976]: Synchronized to time server (time.nist.gov).

You can get more information by:

$ man 5 timesyncd.conf
$ man 8 systemd-timesyncd.service

Time server settings are saved in /etc/ntp.conf so open your favorite editor and make this simple change.

sudo vi /etc/ntp.conf

The relevant section looks something like this (It may say ubuntu instead of debian, but it is the same problem either way):

enter image description here

So all you need to do is change it to look like this on all the relevant computers:

enter image description here

then reboot them.

Voila, the systems are now all using the NIST/NBS Master Clock to synchronize. Stratum 1 is the primary source, and Stratum-2 are a single hop away from it.

The pools are anywhere from 12-16, just like Windows when it uses pools.

You can verify that it is working at Level 1 by using this command:

ntpq -p

Which gave me this output:

enter image description here

FileZilla is now running unbelievably faster as it is able to skip more files! Amazing difference. Time synchronization is an excellent experience.

This is the best that can be attained via the Internet.

time.nist.gov is a load balancer that will find the best server for any particular location.

If you want your system to announce the time to you on the hour, you can use this procedure:

16.04 LTS How to make the system announce the time at the top of the hour with eSpeak

In Windows this same change is even easier. Just click on the clock and follow the prompts to change the Internet time to time.nist.gov then update.

By doing that, even transfers into and out of Windows (for hard drive backups) are a LOT faster as it skips files with the same creation date on both sides.

This has a pleasant side-effect of minimizing the amount of time it takes to ROBOCOPY out to a backup drive, too.

If you want Windows to announce the time to you at the top of the hour, use this procedure:


Once all the systems are set to this time source you can hear them announce the time all at the same time.

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