Why a copied running configuration might not work You copied a configuration from a network host into the router's RAM (running-config). The configuration looks correct, but nothing works. What is the most likely cause in this scenario?
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AYou copied the wrong configuration into RAM.
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BYou copied the configuration into flash memory instead.
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CThe copy did not override the shutdown command in running-config.
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DThe IOS became corrupted after the copy command was initiated.
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EThe router reverted to ROMMON due to a bad boot variable.
Answer
Correct Answer: The copy did not override the shutdown command in running-config.
Explanation
Introduction / Context:On Cisco devices, interface state is an explicit configuration element. If an interface is administratively shut down, it will remain down until a no shutdown command is applied, even if you paste or merge a configuration that contains IP addressing and other settings. Understanding merge semantics explains why a seemingly correct running-config may not pass traffic after being copied in.
Given Data / Assumptions:
- You copied a valid-looking configuration into running-config (RAM).
- Interfaces still show administratively down (or line protocol down).
- No device reload occurred; the configuration was merged, not replaced.
Concept / Approach:
Copying or pasting configuration lines merges with the existing running-config; it does not automatically negate pre-existing commands. If an interface previously had the shutdown directive, and your pasted configuration did not include no shutdown, the interface will remain disabled. This is a common oversight when restoring configurations on lab or field devices.
Step-by-Step Solution:
Check interface status with: show interfaces status or show ip interface brief.If interfaces are administratively down, enter interface configuration mode.Apply: no shutdown on each required interface.Verify link and protocol come up; confirm routing neighbors form as expected.Verification / Alternative check:
Use show running-config to ensure no shutdown is present. Confirm L1/L2 status with show interfaces and end-to-end pings or routing adjacencies forming (for example, show ip ospf neighbor).
Why Other Options Are Wrong:
- Wrong config (A) is possible but not the most likely reason when the pasted lines look correct.
- Copying into flash (B) would not alter running-config at all; the prompt states you copied into RAM.
- IOS corruption (D) or ROMMON fallback (E) would present different symptoms (reboots, missing commands, or ROMMON prompt).
Common Pitfalls:
- Assuming copy replaces instead of merges; always include necessary no statements (like no shutdown).
- Forgetting to save changes to startup-config using write memory or copy run start.
Final Answer:
The copy did not override the shutdown command in running-config.