dnsmasq is a lightweight DNS, TFTP and DHCP server. It is intended to provide coupled DNS and DHCP service to a LAN.
If you want to learn active ip leasing information, you can look at the /var/lib/misc/dnsmasq.leases file:
$ cat /var/lib/misc/dnsmasq.leases
1417132679 78:c5:e5:b4:4d:07 172.16.2.153 android-fbe390b0bb404da *
1417134678 20:54:76:e4:d8:a5 172.16.2.125 android-ab6e5d0a524c9c7d *
Output separated by space and first part shows the expire time of the related ip leasing as unix timestamp.
See also man page of dnsmasq