nmap is a powerfull tool, which is known to be a port scanner. But there are other useful situations where it can be used:

1. Query dhcp parameters

   sudo nmap -sU -p 67 --script=dhcp-discover 192.168.178.1

2. Query registered DNS names in a fritz box
   

   sudo nmap -sP -PN -R --dns-servers 192.168.178.1 192.168.178.0/24 | grep -i fritz.box