Synchronize Time Using Other NTP Peers

General Information

Synchronizing time to a central time server and also keeping in sync with a peer server.

This type of setup is a tier two NTP setup, allowing for redundancy if the central source of time is lost. The two peers then agree on a time and provide it locally to other servers.

Lab Setup

The following virtual machines will be used:

  • ( → Central Time Server
  • ( → NTP Server1 syncs with central (also peers with server2)
  • ( → NTP Server2 syncs with central (also peers with server1)

NTP: Central Time Server

Setting up the “central time server” to allow the other servers to sync to it.

  • Server: (
    • This server should already have ntpd installed and working if FreeIPA has been setup.

Ensure that the firewall allows NTP in

firewall-cmd --permanent --add-service=ntp
firewall-cmd --reload

NTP: Client Peering

Setup the NTP clients to sync with the central NTP server and also peer with each other to provide a tier two redundancy. This would allow other servers to sync with them.

  • Servers
    • (
    • (

Install required package

yum install chrony

Enable and start the service

systemctl enable chronyd
systemctl start chronyd

Edit the config file

vim /etc/chrony.conf
# Comment out all server lines, add a new one
server iburst
# On server1: Peer with server2
# On server2: Peer with server1

Ensure that the firewall allows NTP in (on both server1 and server2)

firewall-cmd --permanent --add-service=ntp
firewall-cmd --reload

Restart the service

systemctl restart chronyd

Ensure NTP time sync is enabled

timedatectl set-ntp true

Check status

chronyc sources -v
  • Note: It may take a few minutes for the servers to enter a synced state on the peers.

  • linux_wiki/synchronize_time_using_other_ntp_peers.txt
  • Last modified: 2019/05/25 23:50
  • (external edit)