What is the purpose of the -O option, and how does it complement -sV?

• A. -O performs operating system detection; -sV performs version detection; together they identify the host OS and running services/versions.
• B. -O increases verbose output.
• C. -O schedules the scan timing.
• D. -O disables OS detection.

Answer: (A)

OS detection with -O fingerprints the target’s operating system by sending probes and analyzing the responses. This helps you identify the likely OS family and version, which is valuable alongside service version detection. The -sV option probes open ports to identify running services and their versions. Using both gives a clearer picture: -sV shows what software is exposed, while -O reveals the platform behind those services. Together they let you interpret service fingerprints more accurately and assess potential vulnerabilities based on the operating system, though results can be affected by firewalls or intrusion prevention systems.