Cisco IOS Mode Explained with Examples

Cisco IOS includes several commands for configuring and controlling Cisco devices. Some commands provide information while others allow you to configure and manage a particular feature, or a specific area of the device, or the entire device.

Based on functions, an IOS organizes commands in modes. An IOS mode is a set of commands used to configure similar features or control a specific area of the device. An IOS mode is also known as the IOS access mode or the IOS commands mode.

There are five IOS modes: - user EXEC mode, privileged EXEC mode, global configuration mode, setup mode, and ROMMON mode.

The first three modes allow you to view current settings and configure or modify new or existing settings. The following two modes let you set up the device's initial configuration and troubleshoot the device in an emergency, respectively.

User EXEC Mode

It is the first mode of IOS. When you access an IOS, the IOS always places you in this mode. If configured, the IOS prompts you to enter the password to access this mode. This mode has a few commands that let you view statistics and perform basic troubleshooting. It does not allow you to change any settings. It serves as the entry point to other IOS modes. You can access different modes only through this mode.

Privileged EXEC Mode

It is the second mode of IOS. It includes privileged commands. You can access this mode only from User Exec mode by executing the 'enable' command. Since the 'enable' command lets you access this mode, this mode is also known as the enable mode. To exit this mode or return to User Exec mode, use the 'exit' or the 'end' command. You can use this mode for the following purposes: -

To view, save, and erase device configuration
To take a backup of the current device configuration
To restore the configuration from backup
To install a new IOS image file
To debug or troubleshoot the device
To restart or reload the device

This mode allows you to manage device configuration and IOS image files. However, it does not let you change the device configuration. You can change device configuration only from the configuration mode.

Global configuration mode

This mode includes commands for configuring the device. In this mode, you can configure new settings and change, update, or delete existing settings. To enter this mode, use the 'configure terminal' command in Privilege Exec mode. To exit this mode, use the 'end' or 'exit' command. You can also press the CTRL + Z key combination.

The following image shows how to navigate User Exec, Privilege Exec, and the Global configuration modes.

This mode includes a large number of commands. To organize these commands effectively, it groups similar commands into sub-configuration modes. Sub-configuration modes are IOS-specific. Cisco makes several flavors of IOS software. A sub-configuration mode available in one flavor of IOS may or may not be available in other flavors. The following table lists standard sub-configuration modes available across all IOS flavors.

Sub-configuration mode	Includes commands to
Interface configuration mode	Configure a physical interface of the device
Sub-interface configuration mode	Configure virtual interfaces
Routing protocol configuration mode	Configure a routing protocol
IP access list configuration mode	Configure the built-in security feature of the IOS
Line configuration mode	Configure access modes of the IOS

Setup Mode

When you start an IOS running device, it looks for the device configuration. If it does not find a valid configuration, it places you in this mode. This mode allows you to configure the device's initial settings. It presents a text-based wizard that asks questions about initial settings in a sequence. Based on the answers you provide, it automatically builds the initial configuration.

ROMMON Mode

During the boot process, the IOS image file loads into RAM. If the IOS image file is missing or corrupt, the device automatically enters this mode. This mode allows you to troubleshoot the IOS. In this mode, you can select a different IOS image file to boot the device or load a new IOS image file from the TFTP server.

The following image shows how all IOS modes work together.

Cisco IOS modes navigation

The following table lists commands to navigate the different IOS modes.

Mode	Prompt	Command to enter	Command to exit
User EXEC	Router >	Default mode after booting. Log in with the configured password.	Use the exit command
Privileged EXEC	Router#	Use the enable command from the user exec mode	Use the exit or end command
Global Configuration	Router(config)#	Use the 'configure terminal' command from the privileged exec mode	Use the exit command
Interface Configuration	Router(config-if)#	Use the 'interface type number' command from the global configuration mode	Use the exit command to return Global configuration mode
Sub-Interface Configuration	Router(config-subif)	Use the 'interface type sub interface number' command from the global configuration mode or the interface configure mode.	Use the exit command to return to the previous mode. Use the end command to return in the privileged exec mode.
Setup	Parameter[Parameter value]:	After booting, the IOS automatically starts this mode, if it does not detect the running configuration.	Press CTRL+C to abort. Type Yes to save the configuration, or No to exit without saving when asked at the end of the setup program.
ROMMON	ROMMON>	Starts automatically if a functional IOS is missing. To start manually, press CTRL+C during the first 60 seconds of the booting process.	Use the exit command.

Conclusion

Cisco IOS provides a structured environment through its various modes, facilitating device management and configuration. The five primary modes are User Exec, Privileged Exec, Global Configuration, Setup, and ROM Monitor. Each mode serves distinct purposes, from basic command execution and troubleshooting to comprehensive device configuration. User EXEC mode serves as the entry point, allowing you to view basic information without making changes. Privilege Exec grants access to advanced commands essential for managing device settings and configurations. The Global Configuration mode lets you implement configuration changes. Sub-configuration modes provide target-specific functionalities, such as interfaces and routing protocols.

By ComputerNetworkingNotes Updated on 2025-12-01