If you are ever wondering which ip addresses on your network are currently being used, you can use nmap to find out.
For example to scan an entire class C subnet you can use the following command:
‘nmap -v -sP 192.168.1.0/24 |grep up’
This will produce a list of ip addresses which are currently being used.
You can also use this command to find a list of inactive ip addresses when you are looking to add devices to your network:
‘nmap -v -sP 192.168.1.0/24 |grep down’