Computer Hacking Forensic Investigator (CHFI) Practice Exam 2025 - Free CHFI Practice Questions and Comprehensive Study Guide

File signature analysis, often referred to as magic number analysis, focuses on the initial bytes of a file to identify its type and function. The correct choice is based on the common practice in forensic investigations where the first 20 bytes of a file are examined to identify its signature. This segment typically contains specific byte patterns or "magic numbers" that are unique to various file types, allowing investigators to determine the nature of the file.

While looking at fewer bytes, like the first 10, might offer some insight, the additional context gained from extending the analysis to the first 20 bytes provides a greater probability of accurately identifying the file type. This method encompasses a wider range of file signatures used in different file systems and helps in detecting various file formats, including images, documents, executables, and more.

Analyzing more than 20 bytes, while possible, often leads to diminishing returns as many file signatures are established within those first crucial 20 bytes. This is why the selected range of 20 bytes is optimal for identifying a file's type and function in forensic analysis.