An IDS (Intrusion Detection System) is deployed out-of-band, meaning it passively monitors network traffic using a SPAN/mirror port or network tap. It detects and analyzes suspicious traffic without introducing latency since it does not sit in-line.

A. IPS (Intrusion Prevention System) is in-line and can block traffic but may add latency.

C. Load balancer distributes traffic across servers for performance and redundancy, not for threat detection.

D. Firewall filters traffic at the perimeter or internally; it can affect latency but does not provide the same in-depth attack analysis.

References (CompTIA Network+ N10-009):

Domain: Network Security — IDS vs. IPS, in-band vs. out-of-band monitoring, passive detection methods.