A、Only when there is a duplicate IP address caused by a combination of static and dynamic IPaddress allocations

B、On each router that exists between the client and the server

C、Only when a router separates the client from the server

D、Only if the DHCP sever issues a DHCPNAK to the initial request

E、Only when the client is on the same subnet as the server

F、Only when the DHCP pool is out of IP addresses