How to check whether ntp is synchronized in linux

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3 minutes to check: 1. Using the ntpq command, you can monitor the operation of the NTP daemon ntpd and determine its performance, syntax ntpq -p; 2. Use the ntpstat command , will report the synchronization status of the NTP daemon running on the local computer. If it is synchronized, it will return 0, if the clock is not synchronized, it will return 1; 3. Use the timedatectl command, the syntax timedatectl status, and return the result of the NTP synchronized line. The result is yes Synchronize.

NTP is used to synchronize the time of a computer client or server to another server or reference clock source. It uses UTC as the time standard. It is an application layer protocol based on the connectionless IP protocol and UDP protocol. It uses a hierarchical time distribution model. The accuracy that can be obtained depends on the accuracy of the local clock hardware and the delay of equipment and processes. strict control.

There are three commands in Linux that can be used to verify NTP synchronization.

• ntpq: ntpq is a standard NTP query program.

• ntpstat: Display the synchronization status of the network world.

• timedatectl: This controls the system time and date in the systemd system.

Method 1: How to check NTP status using ntpq command?

The ntpq utility is used to monitor the operation of the NTP daemon, ntpd, and determine performance.

The program can be run in interactive mode or controlled with command line parameters. It prints out a list of connected peers by sending multiple queries to the server. If NTP is working properly, you will get output similar to the one below.

ntpq -p

Details:

• -p: Prints a list of peers known to the server and a summary of their status.

Method 2: How to check NTP status using ntpstat command?

ntpstat will report the synchronization status of the NTP daemon (ntpd) running on the local computer. If the local system is found to be in sync with the reference time source, ntpstat will report approximate time accuracy. The ntpstat command returns three status codes depending on the NTP synchronization status. Details are as follows.

• 0: Returns 0 if the clock is in sync.

• 1: Returns 1 if the clock is out of sync.

• 2: Return 2 if clock status is uncertain, e.g. if ntpd is unreachable.

ntpstat

Method 3: How to check NTP status using timedatectl command?

The timedatectl command is used to query and change the system clock and its setting in the systmed system.

timedatectl
or
timedatectl status

More Tips

Chrony is an NTP client replacement. It can synchronize the system clock faster and with higher time accuracy, which is especially useful for systems that are not online all the time.

chronyd is smaller, it uses less memory, and only wakes up the CPU when necessary, which saves power better. It works well even when the network is congested for extended periods of time.

You can use any of the following commands to check Chrony status.

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 display information about the current time source.

# 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