When I say
DHCP subnet I mean that the clients are intended to receive their network configuration via DHCP, not statically.
Let's observe the following situation:
I set up an IP address statically, and set the correct subnet and gateway. I'm presuming that, since the IP on the client is static, the client won't broadcast the DHCP discover. That is why the client doesn't know about the existence of the DHCP sever, and vice versa.
What is the mechanism which prevents the DHCP server to assign the address from the statically set client to some new client which asks for an Ip address?