How to remove VTP domain string: 2 reloads

To restore a IOS switch to a "whole new" state, it is necessary to clear even the "VTP domain" string to null. I thought at first just remove "vlan.dat" followed by a reload would do it, but now I found that I was NOT quite correct!

When a switch is not connected to any other switches, removing "vlan.dat" and a reload is working just fine. But when the switch is connected to many other switches whose VTP domain were configured, it will learn the VTP domain string right away from these switches after reload.

This is a feature of an IOS switch that when VTP is in "no-management-domain" state, it "inherits the management domain name and the VTP configuration revision number" upon it receives the first VTP advertisement.

(IOS switches are like baby ducks which recognize the first animal they see as mother, aren't they!)

I encounter this scenario every time when I reset those switches mounted on a training course rack. It would be almost impossible to "unplug" those LAN cables especially when the rack is on a remote site.

I came up a solution to this problem by 2 reloads:

1. Erase the NVRAM, and reload without saving any running configuration. Now the switch is "Configuration Clean".
   
2. Shutdown all interfaces and save configuration. Delete "vlan.dat" and do another reload. Now the IOS switch is in "VTP clean" state.
   
3. After all other switches have done above 2 steps, re-enable all interfaces and do another erase of NVRAM, and now the switch is back to "Configuration Clean" again. Done!

How about this? I would like to hear better ways to solve it!

Reference:

• Cisco.com, Resetting Catalyst Switches to Factory Defaults 
• Cisco.com, Configuring VTP