When automating host discovery in a target subnet, which approach BEST enhances efficiency and accuracy?

• A. Use a script that configures nmap to perform a host scan and automatically outputs a warning if the identified number of hosts does not match the expected value.
• B. Manually count hosts after scanning
• C. Run port scanning without host discovery
• D. Use a vulnerability scanner instead

Answer: (A)

Automating host discovery with a script that runs a focused Nmap host scan and then automatically flags any mismatch between the found live hosts and the expected count keeps discovery fast, repeatable, and reliable. By scripting the scan, you leverage consistent probing methods (like different ICMP or ARP checks) and immediate parsing of results, so you quickly know exactly how many hosts are up and where discrepancies arise. The automatic warning helps catch changes in the network—new devices, devices that are down, or segments unreachable—without manual tallying, reducing both time and human error.

Manual counting is slow and error-prone, especially on larger subnets, and it doesn’t scale well. Running a port scan without first discovering hosts wastes time on hosts that aren’t up and can produce misleading results. Using a vulnerability scanner is focused on finding flaws, not reliably enumerating live hosts in a subnet, and may add unnecessary overhead to the discovery step.