The correct answer is that the sending server (203.0.113.5) is authorized by the domain’s SPF record, and the DKIM signature validates the email was signed by the domain. When interpreting DKIM and SPF headers together in email investigation, an SPF “pass” result confirms that the originating IP address is listed in the domain’s authorized senders, while a valid DKIM signature cryptographically verifies that the message content and headers were not altered after signing. On the CHFI exam, this scenario tests your ability to correlate authentication results to detect spoofing—a common trap is assuming a single pass means the email is safe, but both must align to rule out forgery. Remember the mnemonic “SPF checks the car, DKIM checks the driver”: SPF verifies the sending server’s permission, while DKIM confirms the domain’s identity and message integrity.
CHFI Application, Email and Cloud Forensics Practice Question
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.
An email investigation reveals that a phishing email was sent from a domain that uses DKIM and SPF. The email headers contain: 'DKIM-Signature: v=1; a=rsa-sha256; d=example.com; s=selector1; bh=...; h=...; b=...' and 'Received-SPF: pass (example.com: domain of sender@example.com designates 203.0.113.5 as permitted sender)'. Which TWO conclusions can be drawn?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The email's DKIM signature is valid
SPF pass indicates the sending IP is authorized; DKIM signature validates the email was signed by the domain. Combined, the email is likely not spoofed.
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 email is definitely legitimate and not spoofed
Why it's wrong here
SPF and DKIM can be bypassed; not definitive.
✓
The email's DKIM signature is valid
Why this is correct
A valid DKIM signature is present.
Related concept
Static NAT maps one inside address to one outside address.
✗
The email was sent from a compromised account
Why it's wrong here
No evidence of compromise; authentication passed.
✗
The email originated from a different domain
Why it's wrong here
DKIM domain matches the sender domain.
✓
The sending server (203.0.113.5) is authorized by the domain's SPF record
Why this is correct
SPF passed, so the IP is authorized.
Related concept
Static NAT maps one inside address to one outside address.
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's DKIM signature is valid — SPF pass indicates the sending IP is authorized; DKIM signature validates the email was signed by the domain. Combined, the email is likely not spoofed.
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.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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. An email investigator receives a suspicious email and examines the headers. The 'Received-SPF: pass (google.com: domain of example.com designates 203.0.113.5 as permitted sender)' header is present. However, the 'From' address is 'admin@example.com' and the 'Return-Path' is 'admin@example.com'. What does this indicate?
medium
✓ A.The email passed SPF alignment for the domain example.com
B.The email originated from 203.0.113.5
C.The email failed SPF check
D.The email is definitely legitimate
Why A: SPF check passed for the domain example.com, meaning the sending server (203.0.113.5) is authorized. This suggests the email is not spoofed from that domain, at least from SPF perspective.
Last reviewed: Jun 21, 2026
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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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