Do you know how to reset a Cisco router to factory defaults w/wo CLI? This tutorial will teach the necessary Cisco IOS commands you have to use in order to restore a Cisco router to its initial factory configuration in the CLI interface whether or not you know the privileged EXEC mode’s password.

The procedures described in this blog post guide apply to routers supporting Cisco IOS software like the 800, 1800, 1841, 1921, 2800, 2900, 2901, 2911, 4300, and 4331 Cisco routers.

Restoring a Cisco router back to its factory settings requires deleting the startup configuration, stored in NVRAM.

How to Reset a Cisco Router to Factory Defaults Using the CLI Interface

If you can log in to the router’s CLI interface and enter privileged EXEC mode, you can remove the startup configuration file, and thus restore the router to factory settings.

To achieve this task in the CLI interface, follow these steps:

Step 1. Connect the router to your computer using the console port, SSH, Telnet, or any other means.

Step 2. Issue the write erase command in privileged EXEC mode to remove the startup configuration file. You can also use the erase startup-config command. It accomplishes the same thing.

R1# erase startup-config
Erasing the nvram filesystem will remove all configuration files! Continue? [confirm]  
[OK]
Erase of nvram: complete
%SYS-7-NV_BLOCK_INIT: Initialized the geometry of nvram

Step 3. Issue the reload command in privileged EXEC mode to restart the router.

R1# reload
System configuration has been modified. Save? [yes/no]: n  
Proceed with reload? [confirm] 
System Bootstrap, Version 15.1(4)M4, RELEASE SOFTWARE (fc1)

omitted output




         --- System Configuration Dialog ---

Would you like to enter the initial configuration dialog? [yes/no]: 

How to Reset a Cisco Router to Factory Settings without Password Using ROMmon Mode

If you cannot access the router’s CLI interface, you can use ROMmon mode to restore the router to its factory configuration. In this router mode, we instruct the device not to copy the contents of the current startup configuration file into the running configuration file after it boots.

In this way, the router builds the running configuration based on the factory defaults. Therefore, it is enough to replace the startup configuration file with the content of the running configuration in order to achieve our goal.

The following steps teach you how to restore a Cisco router to its original factory configuration using the ROMmon mode.

Step 1. Connect your computer to the Cisco router via the console cable, power the router off, and then power it on.

Step 2. While the router is booting, press the Ctrl and Break keys to enter ROMmon.

program load complete, entry point: 0x81000000, size: 0x3bcd3d8
Self decompressing the image :
########
monitor: command "boot" aborted due to user interrupt
rommon 1 > 

Step 3. Issue the confreg 0x2142 command to instruct the router to ignore checking the startup configuration file in the next reload.

rommon 1 >  confreg 0x2142

Step 4. Enter reset to reboot the router.

rommon 2 > reset

Step 5. Type the letter ‘n‘ to ignore setting up the router.

         --- System Configuration Dialog ---

Would you like to enter the initial configuration dialog? [yes/no]: n


Press RETURN to get started!

Step 6. Set the configuration register to 0x2102, the default value, in order to boot normally and apply the startup configuration after each router reboot.

Router> enable
Router# conf t
Router(config)# config-register 0x2102
Router(config)# end
Router#

Step 7. Replace the startup configuration file’s content with the current running configuration.

Router# copy running-config startup-config
Destination filename [startup-config]?  
Building configuration...
[OK]

Step 8. Reboot the router using the reload command.

Router# reload
Proceed with reload? [confirm] 
System Bootstrap, Version 15.1(4)M4, RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 2010 by cisco Systems, Inc.
Total memory size = 512 MB - On-board = 512 MB, DIMM0 = 0 MB
CISCO2901/K9 platform with 524288 Kbytes of main memory
Main memory is configured to 72/-1(On-board/DIMM0) bit mode with ECC disabled


omitted output


         --- System Configuration Dialog ---

Would you like to enter the initial configuration dialog? [yes/no]:




How to Reset a Cisco Router Using the Reset Button

If a Cisco router has a reset button, you can follow this procedure to restore its factory settings using the reset button:

Step 1. If the router is already powered on, power it off and then power it on. Otherwise, power it on.

Step 2. Press and hold the reset button for 10 seconds, and then release it.

Step 3. Wait about 10 minutes until the router lights are solid, then power it off. The router’s original configuration is restored, and the router will boot into it the next time it is powered on.

151 Labs to Help You Pass the CCNA Exam and Make Yourself More Competitive in The Job Market. Download Now!

Related Lessons to How to Reset a Cisco Router to Factory Defaults

Conclusion

I hope this blog post helps you learn something.
Now I’d like to turn it over to you:
What did you like about this tutorial?
Or maybe you have an excellent idea that you think I need to add.
Either way, let me know by leaving a comment below right now.

Mohamed Ouamer
Mohamed Ouamer is a computer science teacher and a self-published author. He taught networking technologies and programming for more than fifteen years. While he loves to share knowledge and write, Mohamed's best passions include spending time with his family, visiting his parents, and learning new things.