CREST Practitioner Security Analyst (CPSA) 2026 – 400 Free Practice Questions to Pass the Exam

The X.400 Standard is associated with the port number 103, which is used for Message Handling Systems (MHS) as defined by the ITU-T. This standard facilitates electronic message handling and is part of the broader framework for messaging protocols. Port 103 is specifically designated for the X.400 protocol traffic, enabling the communication and exchange of structured messages between different systems that conform to this standard.

Understanding this association is crucial for anyone working in network security and data communication, as it highlights how specific protocols utilize designated port numbers to function effectively. In contrast, the other options pertain to different protocols; for instance, port 25 is used for SMTP (Simple Mail Transfer Protocol), port 110 is designated for POP3 (Post Office Protocol version 3), and port 8080 is commonly used for HTTP (HyperText Transfer Protocol) alternative services. This knowledge is fundamental for configuring, securing, and troubleshooting network communications.