Which of the following technologies is used to detect unauthorized attempts to access and manipulate computer systems locally or through the Internet or an intranet?

A DMZ is a network architecture segment that isolates public-facing services from the internal network but does not itself detect unauthorized access attempts.

An Intrusion Detection System (IDS) is purpose-built to monitor network traffic and system activity for signs of unauthorized access, misuse, or policy violations. It analyzes events in real time or near-real time and generates alerts when suspicious patterns are detected. Unlike preventive controls, an IDS focuses on detection and notification, covering both local and remote (Internet/intranet) attack vectors.

A firewall enforces access control rules by blocking or permitting traffic but does not analyze behavior to detect intrusion attempts beyond rule matching.

Packet filtering is a firewall technique that inspects packet headers against static rules and does not perform behavioral or anomaly-based intrusion detection.