What is the key function of a host-based IDS?

A host-based Intrusion Detection System (IDS) primarily focuses on monitoring and analyzing activities on an individual host or device. Its key function is to record suspicious activities that are specific to that host, which includes logging file access, monitoring system calls, detecting changes to system files, and tracking user behavior. This allows it to identify potential threats and anomalies that may not be visible to network-based solutions.

While blocking unauthorized network traffic and filtering traffic at the network switch are functions typically associated with firewalls and network security appliances, the primary focus of a host-based IDS is on the internal activities of a specific system rather than broader network traffic patterns. Analyzing incoming and outgoing traffic alone is also not a primary function of host-based IDS, as this is more characteristic of network-based IDS that examines data packets across the network rather than just those related to a single host. Thus, the ability to monitor and record host-specific events makes the correct answer the central feature of a host-based IDS.