This DHCP Server Callout DLL helps administrator to filter out DHCP Requests to DHCP Server based on MAC Address. When a device or computer tries to connect to network, it shall first try to obtain ip address from DHCP Server. DHCP Server Callout DLL checks if this device MAC address is present in known list of MAC addresses configured by administrators. If it is present, device shall be allowed to obtain ip address or device requests shall be ignored based on action configured by administrator.
Source : Microsoft Windows DHCP Team Blog
