active dhcp leases

Here's a great command using CLI - You can go to the directory where dhcpd.log file is located and do:

tail -f dhcpd.log

That will show you leases as they are being issued by the server in real time.

You can also do:

cat /var/lib/dhcpd/dhcpd.leases to see leases that are in the lease file dhcpd.leases

REF: https://askubuntu.com/questions/219609/how-do-i-show-active-dhcp-leases