How to install and Configure NTP client on CentOS/RHEL to Synchronize the Clock

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NTP, Network Time Protocol, it is an Internet protocol used to synchronize the clocks of computers or servers to some NTP server on internet or intranet. In CentOS, it is very easy to install and configure the ntp client.

Install your NTP client using yum command:

    [[email protected] ~]# yum install ntp
    Loaded plugins: fastestmirror
    Loading mirror speeds from cached hostfile
     * addons: ftp.oss.eznetsols.org
     * base: ftp.oss.eznetsols.org
     * epel: ftp.cuhk.edu.hk
     * extras: ftp.oss.eznetsols.org
     * updates: ftp.oss.eznetsols.org
    Setting up Install Process
    Resolving Dependencies
    --> Running transaction check
    ---> Package ntp.x86_64 0:4.2.2p1-9.el5.centos.2.1 set to be updated
    --> Finished Dependency Resolution
    
    Dependencies Resolved
    
    =====================================================================================
     Package      Arch            Version                            Repository     Size
    =====================================================================================
    Installing:
     ntp          x86_64          4.2.2p1-9.el5.centos.2.1           base          1.3 M
    
    Transaction Summary
    =====================================================================================
    Install       1 Package(s)
    Upgrade       0 Package(s)
    
    Total download size: 1.3 M
    Is this ok [y/N]: y
    Downloading Packages:
    ntp-4.2.2p1-9.el5.centos.2.1.x86_64.rpm                       | 1.3 MB     00:04
    Running rpm_check_debug
    Running Transaction Test
    Finished Transaction Test
    Transaction Test Succeeded
    Running Transaction
      Installing     : ntp                                                           1/1
    
    Installed:
      ntp.x86_64 0:4.2.2p1-9.el5.centos.2.1
    
    Complete!
    

Configure your ntp.conf file and pointing to your NTP server

    [[email protected] ~]# vi /etc/ntp.conf
    
    server 0.centos.pool.ntp.org     //set this to your primary NTP server  - Line 17
    server 1.centos.pool.ntp.org     //set this to your Secondary NTP server (Optional)  - Line 18
    server 2.centos.pool.ntp.org     //set this to your tertiary  NTP server(Optional)  - Line 19
    

As for example :

    server ntp1.server.local
    server ntp2.server.local
    

Restart your ntp client using below command:

    [[email protected] ~]# service ntpd restart
    

or

    [[email protected] ~]# /etc/init.d/ntpd restart
    

Test your ntp client status whether properly configured or not by running below command:

    [[email protected] ~]# ntpq -p
    


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