CREST Practitioner Security Analyst (CPSA) Practice

Which port is used by the X11 windowing system?

1. 5900

2. 6000

3. 5000

4. 5432

The correct answer is: 6000

The X11 windowing system, primarily used in UNIX and Linux environments, commonly utilizes port 6000. This protocol facilitates the graphical display of applications running on remote servers, enabling users to interact with these applications as if they were running locally. Port 6000 serves as the default for the X11 server, while subsequent increments (like 6001, 6002, etc.) are utilized for additional displays associated with the same server. Understanding the context of other options adds to the clarity; for instance, port 5900 is typically associated with VNC (Virtual Network Computing), which is a different method for remote desktop functionality. Ports 5000 and 5432 are also reserved for different services, such as UPnP and PostgreSQL, respectively, and do not relate to the X11 windowing system. Therefore, the designation of port 6000 as the primary communication channel for X11 makes it a critical component in remote graphical interface management and interaction.