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CS0-003 · Question #483

A security analyst reviews a SIEM alert related to a suspicious email and wants to verify the authenticity of the message: SPF = PASS DKIM = FAIL DMARC = FAIL Which of the following did the analyst…

The correct answer is B. The message was sent from an authorized mail server but was not signed. The SPF = PASS result confirms the email came from an authorized server, but DKIM = FAIL indicates the message was not properly signed with the expected DomainKeys Identified Mail (DKIM) signature. DMARC = FAIL suggests that because DKIM failed, the overall email authentication…

Submitted by stefanr· Mar 6, 2026Security operations

Question

A security analyst reviews a SIEM alert related to a suspicious email and wants to verify the authenticity of the message:

SPF = PASS DKIM = FAIL DMARC = FAIL Which of the following did the analyst most likely discover?

Options

  • AAn insider threat altered email security records to mask suspicious DNS resolution traffic.
  • BThe message was sent from an authorized mail server but was not signed.
  • CLog normalization corrupted the data as it was brought into the central repository.
  • DThe email security software did not process all of the records correctly.

How the community answered

(27 responses)
  • A
    4% (1)
  • B
    81% (22)
  • C
    4% (1)
  • D
    11% (3)

Explanation

The SPF = PASS result confirms the email came from an authorized server, but DKIM = FAIL indicates the message was not properly signed with the expected DomainKeys Identified Mail (DKIM) signature. DMARC = FAIL suggests that because DKIM failed, the overall email authentication failed. This scenario is consistent with a legitimate server sending an unsigned

Topics

#email security#SPF#DKIM#DMARC#email spoofing

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