Certified Ethical Hacker (CEH v10) — Question 45

You perform a scan of your company's network and discover that TCP port 123 is open. What services by default run on TCP port 123?

Answer options

• A. Telnet
• B. POP3
• C. Network Time Protocol
• D. DNS

Correct answer: C

Explanation

The correct answer is C, as the Network Time Protocol (NTP) operates on TCP port 123 by default, providing time synchronization services. Options A (Telnet), B (POP3), and D (DNS) are incorrect because they are associated with different ports: Telnet uses port 23, POP3 uses port 110, and DNS primarily uses port 53.