# Operating System

##### Subtopics

- [How to check if the system is synchronized?](https://lhc.advantest.com/link/13#bkmrk-how-to-check-if-the--1)
- [How to configure RHEL7 with **ntp**?](https://lhc.advantest.com/link/13#bkmrk-how-to-configure-rhe)
- [How to configure RHEL9 with **chrony**?](https://lhc.advantest.com/link/13#bkmrk-how-to-configure-rhe-1)

### How to check if the system is synchronized?

On RHEL7 the time synchronization is done via **ntp** and on RHEL9 via **chrony**. For license checkout either the license server(s) and the clients need to be synchronized timely.

Please check with

```
timedatectl
```

if the system is **synchronized**.

<div class="imagePlugin hasCaption" data-alignment="Center" data-captiontext="timedatectl output" data-contentprovider="undefined" data-encodedimage="undefined" data-height="355" data-imagenaturalheight="355" data-imagenaturalwidth="540" data-imageurl="/sites/GlobalLicensingPlatform/SiteAssets/SitePages/General-Licensing-Questions/881957280-timedatectl.png" data-insertionisotimestamp="undefined" data-listid="e3b33fd5-515c-4c78-be61-74e77067428e" data-siteid="6c3cb63a-b6cf-434c-9a74-8949665ffc3c" data-stockmediaid="undefined" data-uniqueid="6fca9c68-0dcd-494a-ac73-599280a4fe60" data-uploading="0" data-webid="474b6808-b6f8-4dec-8b7f-2813d573b255" data-width="540" id="bkmrk-timedatectl-output"><div class="i_EO-yY_y298L" id="bkmrk-timedatectl-output-1"><div class="i_Z9-3g_bAiCW css-159 align-center" data-automation-id="imageRead"><figure aria-label="timedatectl output" class="f_Xfb4y_bAiCW p_RdMq6_bAiCW" tabindex="0"><div class="i_-JvIL_bAiCW"><div class="r_L1sJw_fgh7s c_Y4uF4_fgh7s">[![13.webp](https://lhc.advantest.com/uploads/images/gallery/2025-10/scaled-1680-/13-webp.webp)](https://lhc.advantest.com/uploads/images/gallery/2025-10/scaled-1680-/13-webp.webp)</div></div><figcaption class="c_HXzQD_bAiCW" data-automation-id="captionElement-imageRead" title="timedatectl output">*<span id="bkmrk-timedatectl-output-2">timedatectl output</span>*</figcaption></figure></div></div></div>In the screenshot above the system is not configured for time synchronization and **ntp** is disabled.

### How to configure RHEL7 with ntp?

<p class="callout info"><span class="highlightColorYellow">**Note**</span>: In general customer IT is responsible to set up the time synchronization. The information below is just for your convenience, but is not part of GLPT support.</p>

##### **Prerequisite:** 

You need a reliable time server.

Steps to be checked:

1. Check if **ntp** is installed with  
    `rpm -q ntp`  
      
    If it is not installed, you can try to get it with  
    `sudo yum install ntp`
2. open` /etc/ntp.conf` with an editor (you need editing permissions or `sudo` rights)  
    Here you can add the NTP server with adding the line  
    server hostname `iburst`  
    **Example**:  
    `server time.google.com iburst`
3. Check if **ntp** service is enabled / started with  
    `systemctl status ntpd`  
      
    ***If it is not started / enabled***
    
    
    1. Enable **ntp** service for being started with a reboot:  
        `sudo systemctl enable ntpd`
    2. Start **ntp** service with  
        `sudo systemctl start ntpd`
4. Check the time synchronization:   
    `sudo ntpq -p`  
    The **ntpq** command queries the **ntp** servers defined and you get with **option -p** a table back with statistics.
5. Check with `timedatectl`, if **ntp** is enabled and synchronized.  
    ***If ntp is still not enabled***, use:  
      
    `sudo timedatectl set-ntp true`  
    `sudo systemctl start ntpd`  
    Wait a minute and check with `timedatectl` again.

#### **Addition from user experience**

From user experience: even with configuring, enabling and starting the **ntp** daemon the synchronization status was still no (because the time servers configured had an offset). Using

```
sudo systemctl stop ntpd<br></br><br></br>sudo ntpd -gq<br></br><br></br>sudo systemctl start ntpd
```

helped here. The options are for (see also [https://www.tekopolis.com/sync-ntp-immediately-linux/](https://www.tekopolis.com/sync-ntp-immediately-linux/))

1. **option -q**: overrides the built in sanity check of 1000s. If the system time is over 1000s off from the configured server time, the ntpd process would quit otherwise.
2. **option -q**: for quitting the daemon after the clock has been set

### How to configure RHEL9 with chrony?

<p class="callout info"><span class="highlightColorYellow">**Note**</span>: In general customer IT is responsible to set up the time synchronization. The information below is just for your convenience, but is not part of GLPT support.</p>

##### **Prerequisite:** 

You need a reliable time server.

Steps to be checked:

1. Check if `chrony` is installed with  
    `rpm -q chrony`  
      
    ***If it is not installed***, you can try to install it with  
    `sudo yum install chrony`
2. open `/etc/chrony.conf` with an editor (you need editing permissions or sudo rights)  
    Here you can add the time server with adding the line  
    `server hostname iburst`  
      
    **Example:**  
    `server time.google.com iburst`
3. Check if `chrony` service is enabled / started with  
    `systemctl status chronyd`  
      
    ***If it is not started / enabled***
    
    
    1. Enable `chrony` service for being started with a reboot:  
        `sudo systemctl enable chronyd`
    2. Start `chronyd` service with  
        `sudo systemctl start chronyd`
4. Check with `timedatectl`, if `chrony `is enabled and synchronized.