Which is an example of a preventative control type?

An advanced network appliance is an example of a preventative control type because it is designed to proactively protect network resources from various threats before they can exploit vulnerabilities. These appliances often include firewalls, intrusion prevention systems (IPS), and other security measures that analyze traffic and filter out malicious content or unauthorized access attempts. Their primary purpose is to prevent security incidents from occurring in the first place.

In contrast, the other options focus more on detection and response rather than prevention. Network monitoring applications and intrusion detection systems serve primarily to detect and alert on potential security threats and breaches after they occur. They might provide insights into network activity or highlight unusual behavior, but their core function is not to prevent incidents. Similarly, real-time monitoring alerts inform administrators of threats but do not actively block or mitigate them. Thus, the advanced network appliance stands out as a definitive preventative measure in the context of security controls.