CHFI Computer Forensics Fundamentals and Process Practice Question
An analyst runs 'dcfldd if=/dev/sdb of=/evidence/disk.dd hash=sha256 hashlog=/evidence/hash.log' on a Linux system. What is the primary advantage of using dcfldd over plain dd for forensic imaging?
⚠ Common exam trap
Candidates often confuse dcfldd's on-the-fly hashing with other features like compression or memory acquisition, or assume that dd itself can perform hashing, when in fact plain dd has no built-in hash computation capability.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
It can compute hashes on-the-fly and log them
D is correct because dcfldd is a specialized forensic version of dd that can compute cryptographic hashes (e.g., SHA-256) on-the-fly while writing the image, and log those hashes to a separate file (hashlog). This ensures data integrity verification without requiring a separate post-imaging hashing pass, which is a critical requirement in forensic imaging to prove the acquired image is an exact bit-for-bit copy of the source.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
It can acquire memory dumps from live systems
Why it's wrong here
dcfldd is a forensically enhanced version of dd designed for disk imaging; it reads block devices such as /dev/sdb, not volatile memory. Acquiring memory dumps from live systems requires specialized tools that interface with the operating system's memory manager or use hardware mechanisms (e.g., WinPmem, /dev/mem, or hibernation files). dcfldd has no capability to address physical RAM, and running it on a live system would only image the underlying disk, not the system's RAM contents.
- ✗
It supports compression of the output image
Why it's wrong here
dcfldd does not natively support compression; it writes a raw, bit-for-bit replica of the source media. While users can pipe the output to gzip or use named pipes to achieve compression, the tool itself offers no compression flag or built-in algorithm. This is different from forensic formats like E01 or AFF, which include compression natively.
- ✗
It automatically creates a write-blocked connection
Why it's wrong here
dcfldd does not automatically create a write-blocked connection; it simply opens the input and output files as specified. To maintain evidence integrity, examiners must connect the source drive through a hardware write blocker or use a forensic bridge that prevents any writes to the source. The tool itself has no mechanism to enforce read-only access; without a write blocker, the operating system could issue writes during the imaging process.
- ✓
It can compute hashes on-the-fly and log them
Why this is correct
dcfldd computes hash values (MD5, SHA-1, SHA-256, etc.) as it reads data, allowing verification without a separate pass. It can log these hashes to a separate file (e.g., using the 'hashlog' or 'hashlog-md5' parameters) and display verified status for each segment. This is a key forensic feature because it ensures the acquired image is a true copy and provides an audit trail of the imaging process.
Go deeper
Related to this question
About these practice questions
One of 745 original CHFI practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CHFI practice question is part of Courseiva's free EC-Council certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CHFI exam.