Quick Answer
The DKIM-Signature header is the correct choice because it provides a cryptographic signature that authenticates the domain of the sending server and ensures message integrity, directly preventing spoofing. When an email is sent, the outgoing mail server signs the message with a private key, and the receiving server retrieves the corresponding public key from the domain’s DNS records to verify that the email was not altered in transit and genuinely originates from the claimed domain. On the Computer Hacking Forensic Investigator CHFI exam, this concept tests your understanding of email forensics and authentication mechanisms, often appearing in questions about header analysis to trace spoofed or phishing emails. A common trap is confusing DKIM with SPF or DMARC—remember that DKIM focuses on a digital signature tied to the domain, not just IP authorization. Memory tip: think “DKIM = Digital Key Integrity Match,” linking the signature to domain verification.
This CHFI practice question tests your understanding of application, email and cloud forensics. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Which of the following email headers is used to verify the domain of the sending server and is commonly used for authentication to prevent spoofing?
Content-Type
Why wrong: Content-Type specifies the MIME type of the message body.
Received
Why wrong: The Received header tracks the path of the email but does not provide domain verification.
X-Mailer
Why wrong: X-Mailer identifies the email client software, not authentication.
DKIM-Signature
DKIM-Signature provides a digital signature for domain verification.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
DKIM-Signature
The DKIM-Signature header contains a cryptographic signature that allows the receiver to verify that the email was not modified and is from the claimed domain, helping prevent spoofing.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Content-Type
Why it's wrong here
Content-Type specifies the MIME type of the message body.
Received
Why it's wrong here
The Received header tracks the path of the email but does not provide domain verification.
X-Mailer
Why it's wrong here
X-Mailer identifies the email client software, not authentication.
DKIM-Signature
Why this is correct
DKIM-Signature provides a digital signature for domain verification.
Related concept
Static NAT maps one inside address to one outside address.
Common exam traps
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related CHFI NAT questions on configuration and troubleshooting.
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FAQ
Application, Email and Cloud Forensics — This question tests Application, Email and Cloud Forensics — Static NAT maps one inside address to one outside address..
The correct answer is: DKIM-Signature — The DKIM-Signature header contains a cryptographic signature that allows the receiver to verify that the email was not modified and is from the claimed domain, helping prevent spoofing.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related CHFI NAT questions on configuration and troubleshooting.
Static NAT maps one inside address to one outside address.
About these practice questions
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Same concept, more angles
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Which email header field is used to verify that an email was sent by the authorized mail server for the domain and has not been tampered with, using cryptographic signatures?
easyWhy D: DKIM (DomainKeys Identified Mail) uses a digital signature to verify the email's origin and integrity.
Variation 2. Which email header field is specifically used to verify that an email was not tampered with during transit and is signed by the sender's domain?
easyWhy D: DKIM-Signature header contains a digital signature that allows the receiver to verify the email's integrity and authenticity.
Last reviewed: Jun 21, 2026
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.
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