On a Cisco Catalyst 2950 switch, which combination of actions correctly erases the old configuration so that the device starts with factory defaults?

Introduction / Context:
When reusing a Cisco Catalyst 2950 or similar switch, you often need to completely remove the previous configuration, including startup configuration and VLAN information. Cisco exams frequently test your knowledge of the correct sequence of commands to return a switch to a factory default state.

Given Data / Assumptions:

• The device is a Catalyst 2950 switch with nonvolatile memory that stores startup configuration and a separate VLAN database.
• You want to erase the existing configuration so that the switch boots as if it were new.
• Typical commands include erasing startup configuration, deleting the VLAN database file, and reloading the device.

Concept / Approach:
On many Cisco switches, the startup configuration is stored in NVRAM and erased using the erase startup-config or write erase command. VLAN information is often stored in a separate file, usually vlan.dat, in flash memory. To completely clear the configuration, both the startup configuration and VLAN database must be removed, and then the switch must be reloaded so that it starts without any saved configuration.

Step-by-Step Solution:
Step 1: Use erase startup-config or write erase to remove the NVRAM startup configuration file that contains interface settings, passwords, and other parameters.Step 2: Use delete flash:vlan.dat or a similar command to delete the VLAN database file that stores VLAN and VTP information.Step 3: Confirm the deletion of the vlan.dat file when prompted so that the VLAN configuration is truly removed.Step 4: Reload the switch so that it boots without any startup configuration or VLAN database; on reload, it will behave like a factory default device.

Verification / Alternative check:
After performing these steps and reloading, the switch should prompt for initial configuration dialog, and show vlan should display only the default VLAN 1 without any custom VLANs. The running configuration should be minimal, confirming that the old configuration has been erased.

Why Other Options Are Wrong:
Option B incorrectly erases flash, which removes IOS images and other files instead of just configuration, and it does not mention the VLAN database explicitly.Option C suggests that simply restarting the switch clears the configuration, which is false; configuration persists across reboots unless erased.Option D combines actions that are either unnecessary or harmful, such as erasing flash and relying on power-off time, and does not properly address VLAN database handling.

Common Pitfalls:
Technicians sometimes erase only the startup configuration and forget to delete vlan.dat, leaving old VLANs in place. Others mistakenly erase flash and remove the IOS image. Knowing the proper sequence helps avoid downtime and ensures the switch truly starts clean.

Final Answer:
The correct set of actions is to Delete the VLAN database file, erase the startup configuration, and then reload the switch.