As far as I know, with DHCP it has to be released and renewed. The reason is the duration of the original lease. By default, in Microsoft's DHCP server, it has an 8 day lease, this would be true of the Dynamic and the Reserved Addresses. The difference is that with a dynamically assigned address, Wes could have received a different IP address at the end of the lease. With the reservation, at the end of the lease, Wes would have received the same address again because it's mapped to the MAC address.
Either way, Wes machine would not have released the address until the end the lease. The admin could change the reservation and provide a different address but Wes would have not received the address until he released it or rebooted the computer. Rebooting the computer could cause it without having the user issue the
ipconfig /release and
Anyone, know any differently, please chime in!