1.4 Identify interface and cable issues (collisions, errors, mismatch duplex, and/or speed).
Objective 1.4 sits in Network Fundamentals, which carries 20% of the CCNA exam. The questions below are original, written from the official objective title above, and each explanation cites the Cisco page it rests on.
Objective title verbatim from the official objectives. Cisco exam page ↗
A worked example
Shown solved, with the whole explanation open: this is what every question here carries.
Users on this access port report intermittent connectivity and slow transfers.
Switch# show interfaces GigabitEthernet1/0/12
GigabitEthernet1/0/12 is up, line protocol is up (connected)
Hardware is Gigabit Ethernet, address is 00a3.8e21.4c0c
MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec
Full-duplex, 100Mb/s, media type is 10/100/1000BaseTX
4193 input errors, 2871 CRC, 1102 frame, 0 overrun, 0 ignored
0 output errors, 0 collisions, 0 interface resets
0 babbles, 0 late collision, 0 deferredWhat do the counters point to?
The concept
Layer 1 error counters only mean something read against the operating state of the port. Counts that are routine on a shared segment become evidence of a fault when the interface reports full-duplex, since full-duplex switches collision detection off entirely.
Why this answer
This port is running full-duplex, so the collision counter is inactive and reads zero as expected. It is still counting CRC and frame errors on input, and Cisco's counter table names exactly that pattern as the signature to chase: the far end is running half-duplex, senses the wire busy mid-frame, and truncates or corrupts frames the switch then discards.
- AFrames past the MTU land in the giants counter, which is not incrementing anywhere in this output.
- BQueue exhaustion shows as Total output drops or Xmit-Err, and this interface reports neither.
- CFrames in the wrong broadcast domain still arrive intact. A VLAN fault does not corrupt the frame check sequence.
- Correct. CRC and frame errors on a full-duplex port point at the far end running half.
Now you: objective 1.4 questions
No account needed. The explanation opens when you answer.
Sample question 1 of 2
A half-duplex 10 Mb segment has been up for a week and a user reports slow file copies.
Router# show interface ethernet 0
Ethernet0 is up, line protocol is up
Half-duplex, 10Mb/s
2058015 packets input, 233768993 bytes, 1 no buffer
Received 1880947 broadcasts, 0 runts, 0 giants, 1 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 3 ignored
298036 packets output, 32280269 bytes, 0 underruns
0 output errors, 10 collisions, 0 interface resets
0 babbles, 0 late collision, 143 deferredWhat do the collision and deferred values indicate?
Sample question 2 of 2
A server on this 100 Mb port is fed by traffic arriving on a gigabit uplink.
Switch# show interfaces FastEthernet0/24
FastEthernet0/24 is up, line protocol is up (connected)
Full-duplex, 100Mb/s
Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 184392
Output queue: 40/40 (size/max)
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 output errors, 0 collisions, 0 interface resetsWhat explains the output drops?
That’s 2 of the full CCNA bank.
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Continue practicingRead the sources
These are the official pages the questions above cite. Reading them is studying the objective from the primary source, which is what the explanations point you toward anyway.