So here's more details regarding my test lab [i've put the wrong IP Addresses but the configuration remain the same]
Cable Modem ===> Firewall ===> Switch L3 ===> VMWare Esxi ===> Nothing here that can offer IP Addresses, nothing upstream either ==== > W2012R2 - Static IP : 10.115.115.254/24 DHCP Server Range 10.115.115.50 to 75 ===> WAN pfSense ===> LAN pfSense VM Host-only 10.12.12.X/24 ===> Windows 7 VM
So, even if i put the DHCP Server Address 10.115.115.254, i still get an IP Address from 10.115.115.50 to 75.
There's nothing upstream, so it simulate the problem i was having.
If my ISP doesn't offer an IP Address or goes offline, my cable modem should kick in and offer me => 192.168.100.X .
So basicaly in my test lab, if i've configure to reject an IP Address from the DHCP server, i shouldn't get an IP Address at all, so i shouldn't get an IP Address from 10.115.115.50 to 75 ….. right ?