What is the effect of the -R option and when would you want to use it?

• A. It disables DNS resolution entirely.
• B. It queries DNS for at least one target only.
• C. It forces DNS resolution for all targets; use when you need hostnames for logging or verification, but adds overhead.
• D. It slows down the scan but doesn't affect results.

Answer: (C)

The option is about forcing DNS lookups for every target. It makes Nmap attempt to resolve the IPs of all targets to hostnames, so you’ll see names in the output instead of just numbers. This is handy when you need human-readable identifiers for logging or verification, such as matching results to known machines or documentation. The trade-off is the added overhead from DNS queries, which can slow down the scan and introduce potential delays if DNS is slow or unreachable. Use it when having hostnames is important for your workflow, and you’re willing to pay the extra time for those lookups.