Some users want to downgrade the firmware of the mobile, but mobiles like Huawei Y3 ( CRO-L23 ) have "Anti-Rollback" protection. That is, installing old firmware is not allowed. At this time, using the DA Auth File allows you to bypass the Anti-Rollback limit. This file temporarily allows the SP Flash Tool to bypass boot security so that the old firmware can be installed successfully. However, this should be done carefully, otherwise the device may be hard bricked.
In Huawei Y3 ( CRO-L23 ) mobiles, sometimes the preloader gets corrupted and the phone becomes completely dead. It neither connects to the PC nor responds to the charger. At this time, the combination of DA Auth File and Test Point is the only solution. The DA file revives the mobile's bootrom, and the test point gives a connection by shorting it from the hardware-level. This advanced technique is only for experts, but it is not possible without the DA file.