Manually Configuring NTP in the Network 

The easiest way to use a time server in the network is to set server parameters. For example, if a time server called ntp.example.com is reachable from the network, add its name to the file /etc/ntp.conf by adding the following line:

Dynamic Time Synchronization at Runtime

If the system boots without network connection, ntpd starts up, but it cannot resolve DNS names of the time servers set in the configuration file. This can happen if you use Network Manager with an encrypted WLAN.

If you want ntpd to resolve DNS names at runtime, you must set the dynamic option. Then, when the network is establish some time after booting, ntpd looks up the names again and can reach the time servers to get the time.

Manually edit /etc/ntp.conf and add dynamic to one or more server entries:

Or use YaST and proceed as follows:

  1. In YaST click Network Services › NTP Configuration.
  2. Select the server you want to configure. Then click Edit.
  3. Activate the Options field and add dynamic. Separate it with a space, if there are already other options entered.
  4. Click Ok to close the edit dialog. Repeat the previous step to change all servers as wanted.
  5. Finally click Ok to save the settings.

Source : https://documentation.suse.com/