To maintain compliance with regulatory requirements, a security audit of the systems on a network must be performed to determine their compliance with security policies. Which one of the following too

A protocol analyzer (packet sniffer) captures and decodes network traffic for troubleshooting or forensics but does not assess system configuration or compliance posture.

An Intrusion Detection System (IDS) monitors live network traffic or host activity for signs of active attacks but does not audit systems for configuration compliance with security policies.

A port scanner identifies which network ports are open on a system, providing only a partial view of the attack surface without assessing configuration, patch levels, or policy compliance.

Vulnerability scanners enumerate systems on a network, probe them for known misconfigurations, missing patches, weak settings, and policy violations, then produce reports mapping findings to compliance frameworks. This makes them purpose-built for auditing whether systems meet defined security policies and regulatory requirements such as PCI-DSS, HIPAA, or CIS benchmarks.