Setting up Time Synchronisation with Chrony on RHEL 7

The chronyd service is the default service to synchronise time on RHEL 7.

The Lab

We have two RHEL 7.0 servers available in our lab:

  1. srv1.rhce.local (
  2. srv2.rhce.local (

We are going to configure both servers srv1 and srv2 to synchronise time with our central NTP server ipa.rhce.local as well as use peer synchronisation as a backup.

SELinux set to enforcing mode.

Chronyd Configuration

Install package on both servers srv1 and srv2:

[ALL]# yum install -y chrony

On the server srv1, open /etc/chrony.conf and add the line pointing to an NTP server, in our case ipa.rhce.local:

server ipa.rhce.local iburst
peer srv2.rhce.local
local stratum 10

The server should use peer synchronisation with the server srv2 as a backup.

The last line enables the server to fall back on the internal local hardware clock if external servers cannot be reached. Using local to say that the local clock is stratum 10 makes chrony use the local clock when no timeservers are available. This is good because it makes sure we can disconnect your server from the Internet without getting our clock screwed.

Do the same on the server srv2, but replace the peer address with the server srv1.

Enable and start the chronyd service on both servers:

[ALL]# systemctl enable chronyd && systemctl start chronyd

Ensure that an NTP based network time synchronisation is enabled:

[ALL]# timedatectl set-ntp true


[srv1]# chronyc sources
210 Number of sources = 2
MS Name/IP address    Stratum Poll Reach LastRx Last sample
^* ipa.rhce.local           3   6    17     3   +252us[ +335us] +/- 1523ms
=? srv2.rhce.local          0   6     0   10y     +0ns[   +0ns] +/-    0ns

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