Originally Posted by
llondel
My guess is that the client device connects, gets given 0.2 but then fails to renew the lease before expiry. Something else comes along and the DHCP implementation in the router gives it the lowest currently-free address. Your client then detects the clash and asks for another IP address. Some DHCP implementations will attempt to reserve an IP address for a particular MAC and will only re-use one if it runs out of spare addresses.
The DHCP implementation in both client and server maintain the same clock. Hence, unless the server (router in this case) saves it's lease information in volatile memory and is rebooting itself before the lease time is up, then this scenario shouldn't happen (although 'shouldn't' versus 'can't' is a subtle difference)