Final answer:
Nmap is best described as a port scanner tool used to discover hosts and services on a computer network. While it has features that allow for vulnerability scanning and banner grabbing, its primary function is scanning network ports.
Step-by-step explanation:
Nmap, which stands for Network Mapper, is primarily a port scanner tool. It is used to discover hosts and services on a computer network by sending packets and analyzing the responses. Nmap is versatile and includes features such as host discovery, port scanning, version detection (which may include some banner grabbing), and scripts for vulnerability scanning. However, the most accurate answer to the question is A. Port scanner, since that is Nmap's fundamental function.
Additional Uses of Nmap:
Vulnerability scanning using NSE (Nmap Scripting Engine) scripts.
- Network inventory and managing service upgrade schedules.
- Monitoring host or service uptime.
While Nmap can be used for basic banner grabbing to identify service information and it has scripts to detect vulnerabilities, it is not a specialized vulnerability scanner like Nessus or a honeynet, which is a security mechanism set up to detect or study attacks.