Which Cisco IOS command would produce the following output?
A.
show ip interface
B.
show ip interface brief
C.
show interfaces
D.
show interface brief
Explanation:
The output given in the question is produced with the show interfaces command. This command is used to view
the statistics for the configured interfaces on the router. From the sample output, we can determine the
following facts:
The interface has not been enabled, as indicated by the first line Serial0/0/0 is administratively down. It is
not ready to for to forward packets. To enable it, the no shutdown command should be entered.
Line 3 shows that the subnet mask is 255.255.255.0.
Line 3 shows that the IP address is 134.108.28.8, a public IP address.
Line 6 shows that the encapsulation is HDLC, which is the default.
The interface is NOT connected to a LAN, because it is a serial interface.
Two fields worth mentioning in the output of the show interfaces command are the no buffer and the ignored
fields. The ignored field shows the number of received packets ignored by the interface because the interface
hardware ran low on internal buffers. The no buffer field shows the number of received packets discarded
because there was no buffer space in the main system. When either of these two counters begins to increment,
it could be the result of a broadcast storm.Since the show interfaces command displays the up/down state of the interfaces, it is a good command for
troubleshooting. For example, any time users cannot access a resource that requires them to traverse a router,
it is always a good idea to use show interfaces to take a quick look at the state of the interfaces. In the example
diagram below, users cannot access the resource in the network of the Acme Company from the LAN in the
Ajax Company. The first step would be to execute the show interfaces command in R1 to verify functionality of
the interfaces on R1.
The show ip interface command is incorrect because this command is used to view whether the interfaces
configured for Internet Protocol (IP) are usable. Following is a sample output of the show ip interface command:The show ip interface brief command is incorrect because this command provides an overview of all the
interfaces configured for IP on the router. The following is sample output from the show ip interface brief
command. It can be quite useful for troubleshooting as well. For example, if you cannot ping the Ethernet1
interface from a host on the Ethernet 0 LAN, you could determine from the output below that the Ethernet 1
interface is administratively down.
Router# show ip interface brief
Interface IP-Address OK? Method Status Protocol
Ethernet0 12.17.10.5 YES NVRAM up up
Ethernet1 unassigned YES unset administratively down down
Loopback0 12.17.20.5 YES NVRAM up up
Serial0 12.17.30.5 YES NVRAM up up
The solution here would be to enter configuration mode for the interface Ethernet 1 and enable it with the no
shutdown command.
The show interface brief command is incorrect because this command is not a valid Cisco IOS command.
Objective:
LAN Switching Fundamentals
Sub-Objective:
Troubleshoot interface and cable issues (collisions, errors, duplex, speed)
