In WHMCS, the "Domain Expiry Sync Frequency" setting determines how often WHMCS will communicate with your domain registrar to check for updates on domain expiry dates. This feature ensures that WHMCS has the most up-to-date information about when domains are set to expire.

Here's how you can configure the Domain Expiry Sync Frequency in WHMCS:

1. Log into WHMCS: Access your WHMCS admin panel using your username and password.

2. Navigate to Configuration: Click on the "Configuration" tab in the top navigation menu.

3. Domain Registrars: Under the "System Settings" section, click on "Domain Registrars."

4. Edit Registrar Settings: Find the registrar for which you want to configure the domain expiry sync frequency and click on the "Edit" icon (pencil icon) next to it.

5. Sync Settings Tab: In the registrar settings, look for a tab or section related to domain synchronization. This can vary depending on the registrar.

   • Registrar-Specific Settings: Each registrar may have different options for domain synchronization. Look for an option related to "Domain Expiry Sync Frequency" or a similar term.

   • Expiry Sync Frequency: Set how often WHMCS will check with the registrar for updates on domain expiry dates. This is typically specified in hours.

6. Save Changes: After configuring the domain expiry sync frequency, click the "Save Changes" button to apply your modifications.

7. Repeat for Other Registrars (if needed): If you have multiple registrars, repeat the above steps for each one.

By setting the Domain Expiry Sync Frequency, you can ensure that WHMCS regularly communicates with your registrar to keep track of domain expiry dates. This helps prevent any disruptions in services due to expired domains.

Please note that the availability and location of this setting may vary depending on the specific registrar you are using and the integration with WHMCS. Always refer to the documentation provided by your registrar for specific guidance on configuring domain synchronization settings.