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After making configuration changes on a Cisco switch, a network administrator issues a copy running-config startup-config command. What is the result of issuing this command?

• The new configuration will be stored in flash memory.
• The new configuration will be loaded if the switch is restarted.
• The current IOS file will be replaced with the newly configured file.
• The configuration changes will be removed and the original configuration will be restored.

Correct Answer:

2. The new configuration will be loaded if the switch is restarted.

Detailed Explanation:

When working with Cisco switches and routers, network administrators frequently need to make configuration changes to tailor the device’s operation to the specific needs of the network. These changes are typically made in the device’s running configuration, which is the configuration actively being used by the device.

However, the running configuration is stored in volatile memory (RAM), meaning it is temporary and will be lost if the device is powered down or restarted. To ensure that configuration changes are preserved even after a reboot, these changes need to be saved to the startup configuration, which is stored in non-volatile memory (NVRAM).

The command copy running-config startup-config is used for this purpose. Let’s break down the process and the implications of this command.

1. Understanding the Configuration Files:

• Running Configuration: This is the current operational configuration stored in RAM. When you make changes to the configuration of the switch (e.g., adding a VLAN, configuring interfaces, setting up routing protocols), these changes are reflected immediately in the running configuration. However, since it resides in volatile memory, any changes made here will be lost if the device is restarted or loses power.
• Startup Configuration: This is the saved configuration stored in NVRAM. It is non-volatile, meaning it is retained even if the device is powered off or rebooted. The startup configuration is the one that the switch loads during the boot process.

2. The Purpose of copy running-config startup-config:

• When you issue the command copy running-config startup-config, you are essentially telling the switch to take the current running configuration (which includes all the changes you have just made) and save it to the startup configuration file in NVRAM.
• The command has the following syntax:

  Switch# copy running-config startup-config

• This operation copies the entire contents of the running configuration to the startup configuration file. It overwrites the existing startup configuration, ensuring that the next time the switch boots up, it will use the new configuration you have saved.

3. Implications of the Command:

• Preservation of Configuration: By saving the running configuration to the startup configuration, you ensure that all your changes are preserved across reboots. If you did not save the running configuration, any changes made would be lost upon the next restart, and the switch would revert to the previously saved startup configuration.
• Operational Continuity: This is crucial in maintaining network stability and ensuring that all configurations (such as VLAN settings, interface configurations, access lists, etc.) remain in place even after a power cycle or reboot.
• Potential Risks: It’s important to be cautious when saving configurations. If the running configuration contains errors or misconfigurations, these will be saved to the startup configuration as well. Upon reboot, the switch will load this faulty configuration, which could lead to network issues. Therefore, it’s always a good practice to verify the running configuration before saving it.

4. What Happens After Issuing the Command?

• No Immediate Changes: It’s essential to understand that issuing the copy running-config startup-config command does not immediately affect the running configuration. The command only saves the current running configuration to NVRAM. The switch continues to operate using the running configuration as it was before the command was issued.
• Effect on Next Reboot: The saved startup configuration will only take effect when the switch is rebooted. Upon reboot, the switch will load the configuration from NVRAM into RAM, making it the running configuration once again. Thus, the changes you saved with the copy running-config startup-config command will now be active and operational.

5. Why Other Options are Incorrect:

• Option 1: The new configuration will be stored in flash memory.
  • This is incorrect because the copy running-config startup-config command saves the configuration to NVRAM, not flash memory. Flash memory on Cisco devices typically stores the IOS (Internetwork Operating System) image, not the configuration files.
• Option 3: The current IOS file will be replaced with the newly configured file.
  • This is incorrect because the IOS file (stored in flash memory) is the operating system of the device. The command only saves the configuration and does not affect the IOS file.
• Option 4: The configuration changes will be removed and the original configuration will be restored.
  • This is incorrect because the command does the opposite; it saves the current running configuration to the startup configuration. The command to revert to the original startup configuration would involve reloading the device without saving the running configuration.

Conclusion:

The copy running-config startup-config command is a fundamental operation in Cisco device management. It ensures that the configurations made during the current session are retained and applied the next time the device is restarted. This command is crucial for maintaining consistency and reliability in network operations, as it guarantees that the device will load the desired configuration upon reboot, thereby preventing any potential disruptions or misconfigurations that could occur if changes were lost.

Understanding how this command works and its implications is vital for any network administrator working with Cisco devices. Always remember to review the running configuration before saving it, as this step is critical to avoiding unintended consequences due to misconfigurations.