I installed ntp on a centos server.

I modified /etc/ntp.conf replacing the default server entries with one entry to my internal NTP server's IP ( is the IP of the NTP server):

server iburst

When I reboot the server and run ntpstat I see this:

   polling server every 64 s

Then I run sudo ntpdate and see this message:

1 Dec 19:22:35 ntpdate[2339]: the NTP socket is in use, exiting

Then I stop the service (systemctl stop ntpd) and run sudo ntpdate again to see it sync successfully:

1 Dec 19:25:11 ntpdate[2351]: adjust time server offset 0.005316 sec

Now when I start the service back up and run ntpstat I see this message:

synchronised to NTP server ( at stratum 4
   time correct to within 8065 ms
   polling server every 64 s

If I reboot now and run ntpstat it will say unsynchronized. What am I doing wrong? It should be automatically syncing to the IP of the NTP server I put in the config file right?

  • how far off is it if you reboot again? as far as i can see, after running ntpdate and restarting ntpd, everything is fine - ntp makes small adjustments on its own after being 'roughed in'
    – pete
    Dec 2, 2015 at 2:02
  • Wrong time zone on the client, out by too much for the version of ntpd running on it? Not saving time to BIOS on reboot?
    – tink
    Dec 2, 2015 at 2:44

1 Answer 1


Looks like I was just being impatient. After a reboot if I wait about 6 minutes and ran ntpstat it will show it is synchronized.

The polling interval says 64 s which I assumed meant it polls every 64 s, but it looks like it doesn't work like that exactly.

  • 2
    Also, while the NTPD is running and you want to manually sync the time, you need to run this command instead so that it uses a different port (because the daemon is already using it): sudo ntpdate -u Dec 2, 2015 at 17:42

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