ISC2 CC Network Security Practice Question
A security analyst notices unusual traffic from an internal workstation to an external IP address on port 25. Which protocol is most likely being used?
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
✓
SMTP
Port 25 is the default port for SMTP (Simple Mail Transfer Protocol).
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
SMTP
Why this is correct
Correct. SMTP uses port 25 for email transmission.
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FTP
Why it's wrong here
FTP uses ports 20/21.
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DNS
Why it's wrong here
DNS uses port 53.
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HTTP
Why it's wrong here
HTTP uses port 80.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CC practice question is part of Courseiva's free ISC2 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 CC exam.