According to the CHFI v11 objectives under Digital Evidence , Operating System Forensics , and Network-Based Evidence , understanding file-sharing protocols is essential when investigating Network-Attached Storage (NAS) systems. NAS devices are designed to provide shared file access to multiple users over a network, and the most commonly used protocol for this purpose—especially in Windows-based and mixed environments—is SMB/CIFS (Server Message Block / Common Internet File System) .

SMB/CIFS governs how files, folders, printers, and other resources are accessed and shared across the network. By examining SMB/CIFS activity, a forensic investigator can determine which users accessed specific files, when the access occurred, what operations were performed (read, write, delete), and from which systems the access originated . These details are crucial for reconstructing user activity, identifying unauthorized access, and correlating actions across multiple endpoints connected to the NAS.

The other options are incorrect. SMTP (Option A) is an email transmission protocol and unrelated to file sharing. iSCSI (Option B) is a block-level storage protocol used for SAN environments, not user-level file sharing. RAID (Option C) is a disk redundancy technology and does not control how files are accessed over the network.

The CHFI Exam Blueprint v4 highlights SMB/CIFS analysis as a key area for investigating shared storage environments, making it the correct and exam-aligned protocol for understanding file access on NAS devices