Which type of intrusion detection system is focused on monitoring individual machines?

The focus of a host-based intrusion detection system (HIDS) lies in monitoring individual machines, such as servers or workstations. HIDS is designed to track and analyze the behavior of various components within a single device, including operating system files, log files, and application malware. By examining these aspects, it can detect suspicious activities, unauthorized access, or changes to critical system files.

In contrast, a network-based intrusion detection system (NIDS) monitors traffic across the entirety of a network segment, analyzing data packets for abnormal patterns or behaviors. Application-based systems focus specifically on monitoring applications rather than the operating system or hardware aspects, while web-based systems concentrate on monitoring web application traffic to prevent attacks like SQL injection.

Thus, host-based systems uniquely serve to protect individual machines, making it the correct choice in this context.