DHCP Policies provide the DHCP admin with a very effective lever to achieve these scenarios. As of Windows Server 2008 R2, an admin configures an IP address range and option values for a scope/subnet. All clients which are in that scope/subnet get an IP address from this IP address range of the scope and get options configured for the scope. If an administrator of the DHCP server needs to further apportion the IP address range of a scope to be delivered to a specific class of clients or devices or needs to give out different option values to different types of clients - as the aforementioned scenarios demand – there was no way for an admin to achieve that (unless you used individual reservations, which are effort intensive to manage). So, essentially, granularity at which you could assign IP addresses and options existed only up to the scope level. The DHCP policies in Windows Server 2012 help the administrator achieve exactly that – a more granular mechanism to assign IP addresses and options. Five criteria’s that are needed for DHCP POLICIES: MAC Address, Vendor Class, User Class, Client Identifier, Relay Agent Information
MAC, PASS, BOOTP, DHCP DISCOVER.