How do you enter global configuration mode in Cisco IOS?

Entering global configuration mode in Cisco IOS is done by using the command that specifically allows you to access the configuration settings of the device, where you can make changes to the global parameters affecting the overall operation of the router or switch.

The command "configure terminal" is used to transition from privileged EXEC mode (accessed via the "enable" command) to global configuration mode, where various configurations, such as routing protocols, interfaces, and other settings, can be modified. This command indicates that the user is intending to enter the configuration mode from which they can enter additional specific configuration commands.

In contrast, while "enable" is necessary to reach privileged EXEC mode, it does not transition to configuration mode. "exec" is not a command used for this purpose and relates more to EXEC modes, which deal with operational commands rather than configuration. "set mode" is not a recognized command in Cisco IOS for entering global configuration mode. Therefore, "configure terminal" is the correct command that facilitates entering global configuration mode effectively.