Which intrusion detection system is best for large environments with critical assets?

• A. Network-based intrusion detection system (NIDS)
• B. Host-based intrusion detection system (HIDS)
• C. Wireless intrusion detection system (WIDS)
• D. Anomaly-based intrusion detection system (AIDS)

Answer: (A)

For large environments with critical assets, broad visibility across the network is crucial. A network-based IDS provides that by monitoring traffic across network segments from centralized points (like core routers or network taps). This setup offers scalable deployment, centralized management, and the ability to correlate events from many hosts, which is essential when you need to protect numerous systems and detect attacks that span across the network. It helps you see patterns, anomalies, and known attack signatures at a glance, enabling rapid detection and response for the entire environment.

Host-based systems, while providing deep visibility on individual machines, become impractical to scale in big networks because you’d need to install and maintain sensors on countless endpoints. A wireless-focused system targets Wi‑Fi environments specifically, not the entire wired network that typically carries most critical assets. Anomaly-based detection describes a detection approach rather than a deployment scope; it can be used within different IDS types, but on its own it doesn’t define the best fit for large-scale, asset-wide monitoring. In practice, organizations often supplement network-based monitoring with host-based sensors on especially critical hosts for deeper insight, but the question points to the broad, scalable coverage that a network-based IDS provides in large environments.