In which configuration mode can you set a secret password without using line con 0?

The configuration mode in which you can set a secret password without using line con 0 is Global Configuration. In Global Configuration mode, you have the ability to make changes to the overall settings of the device, including setting a secret password that secures access to privileged EXEC mode. This is typically done using the enable secret command, which allows you to specify a password that is encrypted for security purposes.

By configuring the secret password in Global Configuration mode, you can enforce access control policies without needing to configure the console line settings specifically. This approach is aligned with best practices for device security, as it isolates configuration of access controls from user-specific line configurations.

In contrast, Privileged EXEC mode is primarily used for executing commands and does not allow for configuration changes like setting passwords. User EXEC mode restricts access to certain commands and does not permit configuration changes at all. Interface Configuration mode is specifically for configuring interface-specific settings, such as IP addresses, and is not used for setting passwords. Thus, the Global Configuration mode is the appropriate choice for setting a secret password.