When looking at my DHCP server lease log (e.g. the router's log - Asus RT-N12 v126.96.36.199), I find that many (if not all) iPhone and iPad on the network take multiple IP address leases and all on different MAC address.
The main issue with this is that the DHCP server lease range is completely used up. Yes, I can change the subnet address from class C to either B or A, but still, does anyone know why these devices use so many IP addresses (I've seen one with 15 IP addresses assigned to an iPad-2, with 6 more that were expired).
I have set the lease period to 7200 seconds (2 hours), but the expired IP address don't seem to really get released by the device.