In some Huawei Y5 II CUN-L03 mobiles, during flashing, an error like "BROM ERROR: S_SECURITY_SECURE_USB_DL_IMAGE_SIGN_HEADER_NOT_FOUND" occurs which indicates that you are trying to flash a secure partition without a secure signed file. DA Auth File bypasses this error and allows SP Tool to load a signed boot image. This not only eliminates the error but also allows the partition to be restored properly without data loss.
If you have ever tried to repair IMEI on a Huawei Y5 II CUN-L03 mobile, you would know that secure boot often does not allow writing to nvram or nvdata. DA Auth File gives you direct access to nvram so that IMEI can be restored and “No Service” issue can be resolved. Especially in those MTK phones where Meta Mode does not work, reflashing NVRAM with SP Tool using DA file becomes the only solution.