Cisco CCNA mock exam questions sample test – Question 194

Refer to the following partial output of the show interfaces command:
What are the two troubleshooting steps that you should perform to resolve the problem depicted in the output? (Choose two.)

A. Check the cable connections.
B. Reset the equipment.
C. Check the router configuration.
D. Check the router configuration for the shutdown interface command.

Correct Answer: AB

You should check the cable connections and reset the equipment to troubleshoot the problem depicted in the output. The Serial 0 is down, line protocol is down message indicates that there is no carrier detect (CD) signal sensed by the router. This problem might be due to incorrect cabling or a possible hardware failure.

A complete list of the possible troubleshooting steps that should be performed to resolve this issue include:
-Checking the cable connections.
-Resetting the equipment.
-Checking the CD LED on the CSU/DSU.
-Reporting the issue to the leased-line provider.
-Replacing the faulty equipment.

The router configuration is not a possible issue in this scenario because both serial 0 and line protocol are down, indicating a problem in the physical layer. Configuration issues, such as an incorrect IP address, would be indicated in the second section of the output (line protocol is up/down). The second section, regardless of whether it says up or down is meaningless when the first section indicates a problem.

You should not check the router configuration for the shutdown interface command. When an interface has been manually shut down with this command, it will be indicated in the output as Serial 0 is administratively down, line protocol is down.

LAN Switching Fundamentals
Troubleshoot interface and cable issues (collisions, errors, duplex, speed)
Cisco > Cisco IOS Interface and Hardware Component Command Reference > show interfaces summary
Cisco Documentation > Cisco 1700 Series Router Software Configuration Guide > Configuring a Leased Line > Troubleshooting Problems with Leased Lines