How to Set Up and Synchronize NTP Across Multiple Linux Web Servers

Why synchronize time across web servers

When you operate several web servers, their system clocks must stay aligned; the Network Time Protocol (NTP) service ensures consistent timestamps for logs, authentication, and distributed processes.

Step 1: Check NTP status

Run ntpstat. If the output is Unable to talk to NTP daemon. Is it running? , the daemon is not running and should be configured to start on boot. If you see lines such as synchronised to NTP server (198.55.111.5) at stratum 3 , the service is already working. If the output contains unsynchronised , restart the daemon with service ntpd restart to re‑establish synchronization.

Step 2: View NTP peer list

Use ntpq -p to display the list of NTP servers the host is contacting.

Step 3: Manually synchronize time

Execute ntpdate. If you receive the NTP socket is in use. exiting , stop the running daemon first: service ntpd stop, then run ntpdate cn.pool.ntp.org. A successful run prints messages such as adjust time server xxx .

Step 4: Start the NTP service

Start the daemon with service ntpd start. The command should return [ OK ]. To ensure the service starts automatically after a reboot, enable it with chkconfig ntpd on.

Step 5: Verify auto‑start configuration

Run chkconfig --list ntpd. The output should indicate that ntpd is enabled for runlevels 2, 3, 4, and 5 (e.g., ntpd 0:off 1:off 2:on 3:on 4:on 5:on 6:off ), confirming correct boot‑time activation.

Step 6: Customize NTP servers

Edit the NTP configuration file (commonly /etc/ntp.conf) to add or replace server entries with the addresses of preferred time sources. After editing, restart the daemon to apply changes.