What can an investigator examine to verify that a file has the correct extension?

• A. the File Allocation Table
• B. the file header
• C. the file footer
• D. the sector map

Answer: (B)

File headers contain the signature that identifies the true format of a file, independent of its name. This header, often called a magic number, tells you the actual type of content (for example, a PNG starts with a specific byte sequence, a PDF begins with “%PDF-”, etc.). Because extensions are just labels and can be incorrect or misleading, examining the header lets you verify whether the file’s content matches its claimed extension.

The other options don’t reliably indicate the file’s type: the File Allocation Table shows where the file’s data blocks are on disk, not what the data actually is; the sector map is a low-level disk layout detail; and a file footer may exist for some formats but isn’t a universal source of truth for file type.