Change NTP Configuration

Prerequisites

To modify the NTP configuration, you must connect with the root user via your server management tool (iDRAC, iLO, IMM, etc.):

  • Connect to the server management tool.

  • Open a console and connect to the server with the root user.

Procedure

Now you can modify the NTP configuration.

[root@<NODE_NAME> ~]#

vi /etc/chrony.conf

Important

  • You have to keep at least one NTP server or pool.

  • Best practice is to have at least three NTP servers (3 lines beginning with server). Or be synchronized with a pool of multiple NTP servers.

If you want to remove a NTP server or a pool, just delete or comment the line with a # at the beginning of the line.

If you want to add a new NTP pool, add the following line to the file:

pool fr.pool.ntp.org iburst

If you want to add a new NTP server, add the following line to the file:

server 0.fr.pool.ntp.org iburst

If you experience NTP synchronization issues with Windows NTP, for example a server displayed as unusable:

[root@<NODE_NAME> ~]#
chronyc -n sources
MS Name/IP address         Stratum Poll Reach LastRx Last sample
===============================================================================
^? 172.16.96.11                  1   6   377    61   -11.4s[ -11.4s] +/-  11.0s

On the above output, the server 172.16.96.11 is marked with ^?:

  • ^ means this is a server

  • ? means this server is currently unusable.

You can try to increase the maximum distance between the server and the NTP server by adding the following line to the file:

maxdistance 16.0

After you have made the changes, save the file and restart the chronyd service:

[root@<NODE_NAME> ~]#

systemctl restart chronyd

Note

  • Pool servers are a group of NTP servers that are geographically distributed. You can find a list of NTP pools at pool.ntp.org.

  • You can have multiple pools or servers in the configuration file, chronyd will use the more reliable one.

  • The iburst option is used to speed up the initial synchronization.