Which authentication system uses port 88?

Which authentication system uses port 88?

• A. Network Time Protocol (NTP)
• B. NNTP
• C. POP3
• D. Kerberos—authentication system

Answer: (D)

Port numbers identify the service that should handle the traffic. Kerberos, the authentication system, is standardized to use port 88 (typically over UDP, and sometimes TCP when needed). This is why Kerberos traffic is expected on 88 in network configurations and security tooling. The other options correspond to different services with their own ports: time synchronization with NTP uses port 123, NNTP for newsgroups uses port 119, and POP3 for email retrieval uses port 110 (with secure variants using different ports). Since the question is about which authentication system uses port 88, Kerberos is the correct match.

Port numbers identify the service that should handle the traffic. Kerberos, the authentication system, is standardized to use port 88 (typically over UDP, and sometimes TCP when needed). This is why Kerberos traffic is expected on 88 in network configurations and security tooling.

The other options correspond to different services with their own ports: time synchronization with NTP uses port 123, NNTP for newsgroups uses port 119, and POP3 for email retrieval uses port 110 (with secure variants using different ports). Since the question is about which authentication system uses port 88, Kerberos is the correct match.