The DHCP pings the address that it wants to allocate just to check that it is not in use at the moment. The default timeout is 500 ms. I guess if you set this timer high, that should slow it down sufficiently for the primary to get its answer in first. The maximum is 10 seconds. I've never done it that way, so I cannot promise it will work, but you could try it. The command is documented in:
