Clock configuration for time synchronization

In this procedure you will log in to the clock with PuTTY to verify the configuration for time synchronization.

  1. Log in to the clock with PuTTY. See Using PuTTY.
  2. Execute this command to ensure that the NTP process is running on the clock: 
    
# ps -l | grep ntpd
S 0 385 1 14740 13168 0:0 10:14 00:00:00 /usr/sbin/ntpd -g
S 0 474 468 2408 464 pts0 10:17 00:00:00 grep ntpd

    If the ntpd process is not running as shown above, reboot the clock. Once the reboot is complete, repeat step 2 to see if the process is running. If the process is now running but the time on the clock remains incorrect proceed to step 3.

  3. Execute this command to ensure that the correct time server is configured in the ntpd file: 
    
# cat /etc/default/ntpd
# NTP Servers to use for ntpdate
NTPSERVERS="pool.ntp.org"
# Get initial time via ntpdate?
NTPDATE=yes
NTPDATE_OPTS="-t 5"
# Start the ntp daemon?
NTPD=yes

    Confirm that the bolded line above reflects the correct NTP Time Server. The default is always pool.ntp.org but this value could differ if your organization provided a different NTP time server when the clocks were purchased.

    If the time server is incorrect, use the vi editor to correct the entry.

  4. Execute this command to ensure that the correct time server is configured in the ntp.conf file: 
    
# cat /etc/ntp.conf
server pool.ntp.org iburst
# Allow only time queries, at a limited rate, sending KoD when in excess.
# Allow all local queries (IPv4, IPv6)
restrict default nomodify nopeer noquery limited kod
restrict 127.0.0.1
restrict [::1]

    Confirm that the highlighted line above reflects the same time server listed in the ntpd file in step 3.

  5. If the time server is incorrect in either of the files in step 3 or step 4, use vi editor to correct the entry.
  6. To verify if the time server you have configured is correct execute these commands: 
    
# killall ntpd
# ntpdate -v pool.ntp.org
19 Jun 10:54:35 ntpdate[481]: ntpdate 4.2.8p2@1.3265-o Sat Sep 26 20:53:01 UTC 2015 (1)
19 Jun 10:54:42 ntpdate[481]: adjust time server 144.217.65.182 offset -0.004348 sec

    If the result returns the word offset and a time then everything is configured correctly. Check or update the files above with the address supplied for this command. Then reboot the clock and the time will be in synch.

    If the result returns an error message which does NOT include the word offset then the clock cannot reach the time server provided. Consult with your system administrator to verify that the correct time server is being utilized.

    If the changes required in step 4 or step 5 had to be performed reboot the clock to restart the ntpd process. Once the reboot is complete verify if the time is now correct. If the time remains incorrect proceed to step 7.

  7. NTP requires port UDP 123 to be open and accessible to the clock so that the clock can communicate to the default public NTP time server pool.ntp.org. If traffic on this port is restricted then the clock will be unable to synchronize its time. Check with your network administrator to ensure that this port is open.

    If the time server configured is an internal server then check with your system administrator to ensure that the server is available and that its time is correct.