Interface status interpretation After issuing show interface serial 0, you see: “Serial0 is administratively down, line protocol is down.” What does this indicate about the interface state?

Introduction / Context:
Cisco IOS interface status messages help quickly diagnose whether a problem is due to configuration, physical cabling, or protocol negotiation. Understanding the difference between “administratively down” and “down” saves time during triage and points to the right corrective action.

Given Data / Assumptions:

• The interface output states “administratively down, line protocol is down.”
• No additional error messages are given.
• We assume standard IOS behavior and terminology.

Concept / Approach:

“Administratively down” means the interface has been disabled via configuration, typically with the shutdown command under the interface. Because the interface is disabled, the line protocol is also down. This is distinct from an interface that is physically down due to cabling or clocking problems, which would show “Serial0 is down, line protocol is down.”

Step-by-Step Solution:

Verification / Alternative check:

After issuing no shutdown, the first status should change to “up” if the physical layer is good; line protocol will then attempt to come up depending on encapsulation and keepalives.

Why Other Options Are Wrong:

• Mismatched keepalives, missing cable, or PPP failures cause “down/down” or “up/down,” not “administratively down.”
• Pinging from the interface does not toggle administrative state.

Common Pitfalls:

• Confusing “administratively down” with “down” and troubleshooting cabling when the fix is simply no shutdown.

Final Answer:

The administrator has manually shut down the interface.