The correct answer is A. Nmap. Nmap (Network Mapper) is a powerful network scanning and reconnaissance tool specifically designed to gather detailed information about hosts on a network. According to CompTIA Network+ N10-009 objectives, Nmap can be used to identify open ports, running services, and even the operating system of a target device through techniques such as TCP/UDP scanning and OS fingerprinting.
This makes Nmap the best choice when a systems administrator needs a comprehensive view of a server's exposure and configuration. It can enumerate services (e.g., HTTP, SSH), detect service versions, and determine which ports are open, closed, or filtered.
The other options are more limited in scope. Traceroute is used to map the path packets take across a network and identify latency or routing issues, but it does not provide service or OS details. Netstat shows active connections and listening ports on a local machine but does not perform remote OS detection or full service enumeration. Ping simply tests connectivity and reachability using ICMP and does not provide detailed system information.
Therefore, Nmap is the most appropriate and comprehensive tool for this requirement.