NTP - chrony and timedatectl

On EL systems, the chrony NTP client and server is used to synchronize the system’s time.

The configuration file is /etc/chrony.conf; the chronyc and timedatectl commands can be used to monitor the chrony daemon and configure the system clock, respectively.

The default configuration typically point chrony at a NTP pool (distro-specific). Pools are defined with the pool configuration line:

$ cat /etc/chrony.conf | grep pool
# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (https://www.pool.ntp.org/join.html).
pool 2.almalinux.pool.ntp.org iburst

Servers are defined with the server configuration line instead.

If you’re curious, the iburst option simply means “send an initial burst of NTP packets on first contact to sync at startup”.

Pools are DNS records resolved to multiple nearby NTP servers. Servers are single static hosts. These configuration options are separate as Chrony has additional plumbing to query multiple pool members simultaneously, score servers based on response time, stratum, and consistency, drop unreliable servers, and automatically replace dropped servers by querying the pool again - these are not needed if you have just a single defined server.

To enable chrony’s NTP server functionality, you can simply configure the IP allowlist (the allow config line, e.g., allow 192.168.0.0/16) and permit NTP in on your firewall (--add-service=ntp or permit UDP 123).

To list your NTP sources, run chronyc sources:

$ chronyc sources
MS Name/IP address         Stratum Poll Reach LastRx Last sample
===============================================================================
^- 38.28.93.135                  2  10   377   108    +40us[  +40us] +/-   28ms
^* 50.205.57.38                  1  10   377   694    +36us[-5791ns] +/- 6256us
^- 66.85.78.80                   2  10   377   138   -137us[ -137us] +/-   40ms
^- t1.time.gq1.yahoo.com         2  10   377   606   +498us[ +498us] +/-  107ms
^- _gateway                      2   8   377   254   +892us[ +892us] +/-   26ms

To see the details of your NTP daemon (e.g., time offset, skew, update interval), run chronyc tracking:

$ chronyc tracking
Reference ID    : 32CD3926 (50.205.57.38)
Stratum         : 2
Ref time (UTC)  : Sat Apr 25 17:08:24 2026
System time     : 0.000031090 seconds slow of NTP time
Last offset     : -0.000041857 seconds
RMS offset      : 0.000147579 seconds
Frequency       : 4.936 ppm slow
Residual freq   : -0.017 ppm
Skew            : 0.149 ppm
Root delay      : 0.012512143 seconds
Root dispersion : 0.000895039 seconds
Update interval : 1040.9 seconds
Leap status     : Normal

To force an immediate sync, you can run chronyc makestep.

timedatectl status will show you details about the current time zone, local time, and universal time:

$ timedatectl status
               Local time: Sat 2026-04-25 17:20:19 UTC
           Universal time: Sat 2026-04-25 17:20:19 UTC
                 RTC time: Sat 2026-04-25 17:20:19
                Time zone: UTC (UTC, +0000)
System clock synchronized: yes
              NTP service: active
          RTC in local TZ: no

To enable NTP with timedatectl, run, timedatectl set-ntp true.

Perhaps the most general use of timedatectl is for setting your timezone, which you can do with the aptly-named set-timezone parameter. You can run the list-timezones parameter to enumerate available timezones.

$ timedatectl list-timezones | grep New
America/New_York
America/North_Dakota/New_Salem
Canada/Newfoundland

$ sudo timedatectl set-timezone America/New_York

$ timedatectl status
               Local time: Sat 2026-04-25 13:20:41 EDT
           Universal time: Sat 2026-04-25 17:20:41 UTC
                 RTC time: Sat 2026-04-25 17:20:41
                Time zone: America/New_York (EDT, -0400)
System clock synchronized: yes
              NTP service: active
          RTC in local TZ: no

$ date
Sat Apr 25 01:20:44 PM EDT 2026