How to verify whether NTP setup (Sync) is working or not in Linux?
NTP stand for Network Time Protocol, which synchronize the clock between computer systems over the network.
NTP server keep all the servers in-sync with accurate time to perform time based jobs in an organization.
NTP client will synchronize its clock to the network time server.
We had already wrote an article about NTP Server and Client installation and configuration.
If you would like to check these article, navigate to the following links.
- How To Install And Configure NTP Server And NTP Client In Linux?
- How To Install And Configure Chrony As NTP Client?
I assume that we have already setup NTP server and NTP client using the above links.
Now, how to verify whether the NTP setup is working or not?
There are three commands available in Linux to validate the NTP sync. The details are below. In this article, we will tell you, how to verify NTP sync using these commands.
ntpq:ntpq is standard NTP query program.
ntpstat:It shows network time synchronization status.
timedatectl:It controls the system time and date in systemd system.
Method-1: How To Check NTP Status Using ntpq Command?
The ntpq utility program is used to monitor NTP daemon ntpd operations and determine performance.
The program can be run either in interactive mode or controlled using command line arguments.
It prints a list of peers that connected by sending multiple queries to the server.
If NTP is working properly, you will be getting the output similar to below.
# ntpq -p remote refid st t when poll reach delay offset jitter ============================================================================== *CentOS7.2daygee 126.96.36.199 2 u 14 64 37 0.686 0.151 16.432
- -p: Print a list of the peers known to the server as well as a summary of their state.
Method-2: How To Check NTP Status Using ntpstat Command?
ntpstat will report the synchronization state of the NTP daemon (ntpd) running on the local machine.
If the local system is found to be synchronized to a reference time source, ntpstat will report the approximate time accuracy.
The ntpstat command returns three kind of status code based on the NTP sync. The details are below.
0:It returns 0 if clock is synchronised.
1:It returns 1 if clock is not synchronised.
2:It returns 2 if clock state is in-determinant, for example if ntpd is not contactable.
# ntpstat synchronised to NTP server (192.168.1.8) at stratum 3 time correct to within 508 ms polling server every 64 s
Method-3: How To Check NTP Status Using timedatectl Command?
timedatectl Command is used to query and change the system clock and its settings in systmed system.
# timedatectl or # timedatectl status Local time: Thu 2019-05-30 05:01:05 CDT Universal time: Thu 2019-05-30 10:01:05 UTC RTC time: Thu 2019-05-30 10:01:05 Time zone: America/Chicago (CDT, -0500) NTP enabled: yes NTP synchronized: yes RTC in local TZ: no DST active: yes Last DST change: DST began at Sun 2019-03-10 01:59:59 CST Sun 2019-03-10 03:00:00 CDT Next DST change: DST ends (the clock jumps one hour backwards) at Sun 2019-11-03 01:59:59 CDT Sun 2019-11-03 01:00:00 CST
Chrony is replacement of NTP client.
It can synchronize the system clock faster with better time accuracy and it can be very much useful for the systems which are not online all the time.
Chronyd is smaller in size, it uses less system memory and it wakes up the CPU only when necessary, which is better for power saving.
It can perform well even when the network is congested for longer periods of time.
You can use any of the below commands to check Chrony status.
To check chrony tracking status.
# chronyc tracking Reference ID : C0A80105 (CentOS7.2daygeek.com) Stratum : 3 Ref time (UTC) : Thu Mar 28 05:57:27 2019 System time : 0.000002545 seconds slow of NTP time Last offset : +0.001194361 seconds RMS offset : 0.001194361 seconds Frequency : 1.650 ppm fast Residual freq : +184.101 ppm Skew : 2.962 ppm Root delay : 0.107966967 seconds Root dispersion : 1.060455322 seconds Update interval : 2.0 seconds Leap status : Normal
Run the sources command to displays information about the current time sources.
# chronyc sources 210 Number of sources = 1 MS Name/IP address Stratum Poll Reach LastRx Last sample =============================================================================== ^* CentOS7.2daygeek.com 2 6 17 62 +36us[+1230us] +/- 1111ms