You're doing an internal security audit and you want to find out what ports are open on all the servers. What is the best way to find out?

Nmap (Network Mapper) is a purpose-built open-source tool for network discovery and security auditing that can rapidly scan entire IP ranges for open ports, services, and OS details. It supports multiple scan techniques (TCP SYN, UDP, etc.) and can output structured reports, making it ideal for internal security audits at scale.

Physically visiting each server is impractical, time-consuming, and does not reveal network-level port exposure from a remote attacker's perspective.

MBSA (Microsoft Baseline Security Analyzer) checks for missing patches and security misconfigurations on Windows systems, not open network ports.

Manually telnetting to every port on each server is extremely slow, error-prone, and impractical at scale compared to automated scanning tools.