Which of the following is NOT a commonly recognized subtype of IDS?

The concept of Intrusion Detection Systems (IDS) encompasses various subtypes that classify how they operate and monitor for potential threats. Among the recognized types are Host Based IDS (HIDS) and Network Based IDS (NIDS), both of which reflect the specific areas they monitor. HIDS operates on specific devices, monitoring activities and system calls to detect malicious behavior, while NIDS examines the network traffic to identify threats across the entire network.

Signature Based IDS is another valid subtype that assesses traffic based on known patterns (or signatures) of malicious activity. This method relies on a database of known attack signatures to identify and alert on intrusions.

While there are various ways to categorize IDS, "Software Based IDS (SBIDS)" is not recognized as a standard subtype within the field. The term does not refer to a specific operational model or distinct approach that would be universally acknowledged in the cybersecurity community. It doesn’t specify a method related to how an IDS functions, making it lesser-known and less formally categorized compared to the other types. Thus, it fits the context of being NOT a commonly recognized subtype of IDS.