What characterizes a true negative in intrusion detection systems?

In intrusion detection systems (IDS), a true negative is characterized by no attack being detected, where the system correctly identifies that the behavior occurring on the network is acceptable. This means the IDS is functioning effectively by distinguishing normal, legitimate activity from potential threats, indicating that the system is not falsely triggering alerts when there are no security events to report.

In a true negative scenario, the IDS does not raise any alarm or alert, thereby reducing false positives and ensuring that the focus remains on actual threats rather than benign activities. This is crucial for the efficiency of network monitoring and security response.

In contrast, the other options represent situations that do not align with the definition of a true negative: triggering an alarm for unrecognized events signifies a misidentification, a real attack generating an alert is a true positive, and an authentication failure pertains to user access issues rather than an intrusion detection context.