The boot list can be changed by any of the following:
Changing the order in BIOS setup.
Changing the order using a tool (such as BIOSconfig) that manipulates the contents of CMOS and the BIOS boot block structures stored in NVRAM, which is a dedicated part of the BIOS ROM.
Reordering the categories using the IPMI bootflags that the SP offers to the (compatible) BIOS during POST. The default priority order for categories is CD/DVD, disk, removable, and network.