The PXE uses its serial number as the client identifier in the DHCP request. Therefore, to successfully reserve an IP address for the PXE in a Windows® DHCP server, use the PXE device's serial number as the unique ID instead of the MAC address.
Convert the serial number into ASCII codes for the IP address reservation entry. For example, if the PXE device's serial number is PEG1A00003, use the serial number's ASCII codes "50 45 47 31 41 30 30 30 30 33" as the unique ID.