What is the effect of the -F option on port scanning in Nmap?

• A. It enables full port scan of all 65,535 ports.
• B. It reduces the scanned ports from 1,000 down to 100.
• C. It switches to UDP scanning only.
• D. It performs a ping sweep only.

Answer: (B)

The -F option activates Nmap’s fast scan mode. In this mode, Nmap checks a smaller, predefined set of ports—about the 100 most commonly used ones—instead of the default roughly 1,000 ports. This makes the scan much quicker, but you might miss services running on ports outside that top-100 list. It doesn’t switch to UDP-only scanning (that’s a separate flag) and it doesn’t perform a ping sweep; those are different aspects of scanning. It also won’t scan all 65,535 ports unless you explicitly request it with a broader port range.