Which of the following scenarios would most likely require the use of an IPS Sensor?

An IPS (Intrusion Prevention System) Sensor is specifically designed to detect and prevent malicious activities on a network. When faced with a port scanning attack, the intrusion prevention system can identify this malicious behavior, which typically involves sending packets to various ports on a target system to identify open and vulnerable services. By employing an IPS Sensor, the system can automatically take action, such as blocking the offending IP address or initiating a response to mitigate the threat.

In this context, the focus is on actively identifying and stopping attacks in real-time, making the use of an IPS Sensor crucial. Other options like backing up data, monitoring user logins, and configuring user access permissions do not inherently involve real-time threat detection or prevention, which is the primary function of an IPS in maintaining network security. Therefore, the scenario involving a port scanning attack is ideal for the application of an IPS Sensor, as it directly addresses the need for proactive network protection against intrusion attempts.