I work at a University and have been seeing a lot of IP theft from iOS devices. They seem to cache previously used IP addresses on the wireless network and try to reuse those instead of obtaining a new ip address via dhcp. This will prevent users from connecting for hours some times. A workaround is to have users forget the network. I need to know why this happens. How long an address is cached for. And the dhcp process that iOS devices follow when trying to connect to a network. It seems they initially ARP a request to reuse an IP, but packet captures are also showing some icmpv6 and mdns stuff. I never actually see a dhcp discover, offer or request. Just a DHCP NAK.