Geofencing is a technology that allows you to set up virtual boundaries or geographic zones and trigger actions when a mobile device enters or exits those predefined areas. In this case, you can set up a geofence around the sensitive area of the data center, and when a mobile device enters that area, it can trigger an alert to be sent to the security team and optionally notify the individual entering the area that their access has been logged and monitored. Geofencing is commonly used for location-based security and notifications.