Similar to User mode there is a Configuration mode in Cisco Routing.

User mode allows commands that provide information being displayed to the user.

Privileged mode supports a superset of commands compared to user mode.

Configuration mode is another mode in which configuration commands are provided.

Commands typed in configuration mode update the active configuration file.

These changes to the configuration occur immediately each time you press the Enter key at the end of a command.

Configuration mode itself contains a multitude of subcommand modes. The type of command you enter moves you from one configuration subcommand mode to which ever subcommand mode is appropriate.

When multiple instances of a parameter can be set on a single router, the command used to set the parameter is likely a configuration subcommand. Items that are set once for the entire router are likely global commands.

You can use CTRL + Z from any part of configuration mode, or use the exit command from global configuration mode, to exit configuration mode and return to privileged exec mode. The configuration mode end command also exits from any point in the configuration mode back to privileged exec mode.

The exit commands from subcommand modes back up one level toward global configuration mode.