– In some Android custom ROM or modding contexts, "DLC Boot" allowed users to temporarily boot a different kernel or recovery image without permanently flashing it. This was helpful for testing new ROMs or recoveries risk-free, since a simple reboot would return the device to its original state.
If you meant as in Downloadable Content boot on gaming consoles (e.g., Xbox 360 or PS3 modding in 2016), it might refer to a method of launching DLCs that required a specific boot sequence or signature check bypass. dlc boot 2016
However, if you are thinking of a specific device or tool (e.g., "DLC Boot" in RKAndroidTool, Mediatek SP Flash Tool, or U-Boot), please provide more context — I can give a precise, helpful explanation of its use and safety benefits. – In some Android custom ROM or modding