CompTIA Linux+ XK0-006 (V8) Practice Question

The correct answer is the Signature Database (db). The UEFI Secure Boot process uses several key databases to ensure that only trusted code is loaded. The Signature Database (db) contains a whitelist of cryptographic hashes and certificates for trusted UEFI applications, operating system loaders, and drivers. When a new OS update includes a new boot loader, its signature must be present in the db to be considered trusted. In this scenario, the boot failure is most likely because the new boot loader's signature was not added to the db. The Forbidden Signatures Database (dbx) is a blacklist of known malicious or compromised software hashes and would not apply to a new, legitimate update. The Key Exchange Key (KEK) is used to update the db and dbx databases, not to directly verify boot loaders. The Platform Key (PK) is the root of trust and is used to manage the KEK, not for direct verification of boot components.