Here is basic overview of setting up NTP by GUI and also by terminal command. You have to be logged in as root user.
1.) Click on System -> Admin -> Date & Time
2.) Make sure Synchronize is checked. Then add and delete the servers you want. Then Click ok to exit.
3.) To Verify : Open a terminal as root or "su"
It any entry is starred, it means Venice is synced to that server. The entries '+' , means the server is in standby for sync if the currently synced one goes down. If none is starred, wait 5 mins and try again.
Configure NTP by Command Only : -
1.) Open a Terminal and run these commands as root or 'su'.
a.) service ntpd stop <--- Stop NTP service
b.) gedit /etc/ntp.conf & <---here any entries with 'server' at the beginning you want to comment out and add your own server.
For Example in - 'server 0.rhel.pool.ntp.org '. Replace with 'server my_new_ntp_server.com' Then save file and quit.
If your time server is locally hosted (like 192.168.X.X ), check with your IT admin and add exceptions as noted in comments in the ntp.conf file. The default port is 123. If you port is non default , you may have to add that as an exception using command 'iptables'.
c.) service ntpd start <---Start ntp service
d.) chkconfig ntpd on <---Will ensure ntp starts at boot up.
2.) Perform step 3 above to Verify.
Troubleshoot Commands :
How to Test an NTP Server Using Ntpdate - Do you want to check if an NTP server is alive and responding to NTP queries? Do you need to manually check an NTP server to see if the clock is correct?
Try using ntpdate from a linux CLI to query the NTP server.
$ntpdate IP Address
$ ntpdate -q pool.ntp.org
server 18.104.22.168, stratum 2, offset 1.552116, delay 0.06792
server 22.214.171.124, stratum 2, offset 1.556884, delay 0.11574
server 126.96.36.199, stratum 2, offset 1.569006, delay 0.11952
server 188.8.131.52, stratum 2, offset 1.542965, delay 0.11389
19 Apr 21:30:06 ntpdate: step time server 184.108.40.206 offset 1.552116 sec
The -q switch says to query only and not set the time. With this command you can query an NTP server and it will return the date it has set.
Steps to force NTP sync
1. Stop the ntpd service :
# service ntpd stop
2. Force an update :
# ntpd -gq
-g – requests an update irrespective of the time offset
-q – requests the daemon to quit after updating the date from the ntp server.
3. restart the ntpd service :
# service ntpd start
Other Commands :
service ntpd status - Status of the Service
ntpstat - Lists name of server synchronized to.