What is the purpose of the --top-ports option and how would you scan the top 50 ports?

What is the purpose of the --top-ports option and how would you scan the top 50 ports?

• A. It scans the ports from 51-100
• B. It only scans 50 random ports
• C. It increases the timeout by 50 seconds
• D. It scans the most commonly used ports; Use --top-ports 50

Answer: (D)

The main idea is that --top-ports tells Nmap to focus on ports that are most likely to be open because they’re the ones most commonly used by services. Nmap uses a ranking of ports by how frequently they appear in real-world services, and this option makes the scan test only that top subset, which speeds things up and often yields useful results. To scan the top 50 ports, you would run: nmap --top-ports 50 <target>. This directs Nmap to check the 50 ports with the highest probability of being open on the target. The other descriptions don’t fit: scanning a fixed range like 51-100 ignores the popularity ranking; scanning random ports defeats the purpose of prioritizing common ones; and changing timeout has nothing to do with which ports get scanned.

The main idea is that --top-ports tells Nmap to focus on ports that are most likely to be open because they’re the ones most commonly used by services. Nmap uses a ranking of ports by how frequently they appear in real-world services, and this option makes the scan test only that top subset, which speeds things up and often yields useful results.

To scan the top 50 ports, you would run: nmap --top-ports 50 . This directs Nmap to check the 50 ports with the highest probability of being open on the target.

The other descriptions don’t fit: scanning a fixed range like 51-100 ignores the popularity ranking; scanning random ports defeats the purpose of prioritizing common ones; and changing timeout has nothing to do with which ports get scanned.