CHFI Application, Email and Cloud Forensics Practice Question
This CHFI practice question tests your understanding of application, email and cloud forensics. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
An investigator examines an email header and sees the following: 'DKIM-Signature: v=1; a=rsa-sha256; d=example.com; s=selector1; bh=...; h=...; b=...'. The email claims to be from 'support@example.com', but the DKIM signature validation fails. Which of the following is the MOST likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The email was sent from a different domain but the From header was spoofed.
DKIM uses a digital signature to verify the email's domain. Validation failure strongly suggests the email was not sent by the legitimate domain, indicating 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
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
The DKIM signature is optional and can be ignored.
Why it's wrong here
While DKIM is optional, failure to validate indicates potential spoofing.
✓
The email was sent from a different domain but the From header was spoofed.
Why this is correct
DKIM signature failure indicates the email was not signed by the claimed domain's private key, suggesting the From address may be spoofed.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
✗
The recipient's email server does not support DKIM.
Why it's wrong here
DKIM verification is performed by the receiving server; failure is due to signature mismatch, not lack of support.
✗
The email was encrypted and cannot be verified.
Why it's wrong here
DKIM is independent of encryption; it verifies the signature using the public key.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
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
How to think about this question
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.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
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
How this comes up in practice
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CHFI question in full detail.
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.
Application, Email and Cloud Forensics — This question tests Application, Email and Cloud Forensics — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The email was sent from a different domain but the From header was spoofed. — DKIM uses a digital signature to verify the email's domain. Validation failure strongly suggests the email was not sent by the legitimate domain, indicating spoofing.
What should I do if I get this CHFI question wrong?
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.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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Question Discussion
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