The execution of the show interfaces command yields the following as a part of its output:
Ethernet 0/0 is up, line protocol is down
Which of the following can be determined from this output?
A. the link is not functional due to a Data Link layer issue
B. the link is fully functional
C. the link is not functional due to a Physical layer issue
D. the link is not functional due to both a Physical layer and a Data Link layer issue
Correct Answer: A
Explanation:
The command output excerpt indicates that the link is not functional due to a Data Link layer (or “line protocol”) issue, while the Physical layer (Layer 1) is operational. The first (left) column indicates the Physical layer state of the interface, while the second (right) column indicates the Data Link layer state of the interface.
The link is not fully functional. Were it fully functional, the command output would be:
Ethernet0/0 is up, line protocol is up
The link is not suffering a Physical layer issue or a combination of Physical layer and Layer 2 (Data Link) layer issues. Were either the case, the output would be:
Ethernet 0/0 is down, line protocol is down
Note: if a Physical layer issue exists, there will also be a Data Link issue, since the Data Link layer depends on the Physical layer to provide connectivity.