NSE7 Advanced Threat Protection Practice Question
A security administrator wants to block email spoofing attacks against their organization's domain. They configure SPF, DKIM, and DMARC records. Which protocol authenticates the domain of the email sender by verifying the email's signature against a public key published in DNS?
⚠ Common exam trap
Candidates often confuse SPF's IP-based verification with DKIM's cryptographic signature verification, or they assume DMARC performs the actual authentication, when in fact DMARC only enforces policies based on SPF and DKIM results.
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
✓
DKIM
DKIM (DomainKeys Identified Mail) is the correct answer because it provides email authentication by allowing the sender to cryptographically sign an email with a private key. The receiving mail server then retrieves the sender's public key from a DNS TXT record and verifies the signature, confirming that the email was not tampered with and originates from a domain the sender is authorized to use.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
SPF
Why it's wrong here
SPF checks the sending IP address against authorized servers.
- ✗
ARC
Why it's wrong here
ARC preserves email authentication results across intermediaries, not primary authentication.
- ✓
DKIM
Why this is correct
DKIM signs emails with a private key; the public key in DNS verifies the signature.
- ✗
DMARC
Why it's wrong here
DMARC uses SPF and DKIM results to determine policy.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This NSE7 practice question is part of Courseiva's free Fortinet 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 NSE7 exam.