Which configuration mode allows commands that affect the entire router or switch?

Global Configuration Mode is the correct choice because it is the mode in Cisco network devices where you can enter commands that affect the entire device, including both routing and switching functions. In this mode, administrators can modify system-wide settings and configurations, allowing them to manage interfaces, routing protocols, and other essential aspects of the device's operation.

This mode acts as a high-level interface that allows comprehensive control over the device, unlike other modes such as Interface Configuration Mode, which is limited to specific interfaces, or Privileged Exec Mode, where the focus is on executing commands without making direct changes to the system configuration. User Exec Mode provides basic monitoring commands and limited capabilities but does not allow configuration changes. Understanding the distinction between these modes is crucial for effective device management and troubleshooting in a Cisco environment.