A general use of nmap is to discover live hosts from a network, range or list. But what if you want to discover dead hosts. Suppose you have made some changes in network equipment and need to find if all IPs are reachable.
Let’s say you have a list of IP addresses in a file called iplist.txt. To do a host discovery, you just need to run the following command:
nmap -n -R -sP -iL iplist.txt
This command will show down hosts too, not just the alive ones.