Question 1,121 of 2,015
Network AssuranceeasyMultiple ChoiceObjective-mapped

Quick Answer

The answer is a cable or hardware issue causing link flapping. Interface resets occur when the interface loses carrier or experiences a link state change, incrementing the reset counter each time the interface goes down and comes back up. This is almost always a physical layer problem—such as a faulty cable, damaged connector, or failing transceiver—rather than a software or configuration error. On the ENCOR 350-401 exam, this concept tests your ability to distinguish between interface resets and other error counters like CRC errors or collisions, which do not directly cause the interface to reset. A common trap is confusing resets with input errors or output drops; remember that resets specifically track link flaps, not packet corruption. Memory tip: “Resets mean the link left and came back—check the cable, not the config.”

CCNP Network Assurance Practice Question

This 350-401 practice question tests your understanding of network assurance. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.

Exhibit

Refer to the exhibit.

Switch# show interfaces gigabitethernet 1/0/1
GigabitEthernet1/0/1 is up, line protocol is up
  Hardware is Gigabit Ethernet, address is aaaa.bbbb.cccc (bia aaaa.bbbb.cccc)
  MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Full-duplex, 1000Mb/s, link type is auto, media type is 10/100/1000BaseTX
  input flow-control is off, output flow-control is unsupported
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:00, output 00:00:00, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
     0 packets input, 0 bytes, 0 no buffer
     Received 0 broadcasts (0 multicasts)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 0 multicast, 0 pause input
     0 input packets with dribble condition detected
     0 packets output, 0 bytes, 0 underruns
     0 output errors, 0 collisions, 2 interface resets
     0 unknown protocol drops
     0 babbles, 0 late collision, 0 deferred
     0 lost carrier, 0 no carrier, 0 pause output
     0 output buffer failures, 0 output buffers swapped out

Refer to the exhibit. An engineer notices that interface resets have occurred. What is the most likely cause of the interface resets?

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

  • Clue: "most likely"

    Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

Question 1easymultiple choice
Full question →

Exhibit

Refer to the exhibit.

Switch# show interfaces gigabitethernet 1/0/1
GigabitEthernet1/0/1 is up, line protocol is up
  Hardware is Gigabit Ethernet, address is aaaa.bbbb.cccc (bia aaaa.bbbb.cccc)
  MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Full-duplex, 1000Mb/s, link type is auto, media type is 10/100/1000BaseTX
  input flow-control is off, output flow-control is unsupported
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:00, output 00:00:00, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
     0 packets input, 0 bytes, 0 no buffer
     Received 0 broadcasts (0 multicasts)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 0 multicast, 0 pause input
     0 input packets with dribble condition detected
     0 packets output, 0 bytes, 0 underruns
     0 output errors, 0 collisions, 2 interface resets
     0 unknown protocol drops
     0 babbles, 0 late collision, 0 deferred
     0 lost carrier, 0 no carrier, 0 pause output
     0 output buffer failures, 0 output buffers swapped out

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

Cable or hardware issue causing link flapping

Interface resets typically indicate that the interface has gone down and come back up, which is most commonly caused by a physical layer issue such as a faulty cable, damaged connector, or hardware problem that leads to link flapping. When the link flaps, the interface counters increment the 'resets' field, reflecting the number of times the interface has been reset due to a loss of carrier or a link state change. This is distinct from errors like CRC or collisions, which do not directly cause the interface to reset.

Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • Cable or hardware issue causing link flapping

    Why this is correct

    Option C is correct because interface resets often indicate the link went down and up.

    Clue confirmation

    The clue word "most likely" in the question point toward this answer.

    Related concept

    Read the scenario before looking for a memorised answer.

  • CRC errors due to noise

    Why it's wrong here

    Option B is wrong because 0 CRC errors are shown.

  • Collisions on the link

    Why it's wrong here

    Option A is wrong because the output shows 0 collisions.

  • Interface is administratively down

    Why it's wrong here

    Option D is wrong because the interface is up/up.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates often confuse interface resets with CRC errors or collisions, but Cisco specifically tests that resets are caused by physical layer issues (link flapping) rather than data-link layer errors.

Trap categories for this question

  • Command / output trap

    Option B is wrong because 0 CRC errors are shown.

Detailed technical explanation

How to think about this question

Interface resets occur when the hardware detects a loss of carrier (carrier transitions) or when the interface is manually reset via commands like 'clear counters' or 'shutdown/no shutdown'. In Cisco IOS, the 'show interfaces' command displays 'interface resets' as a cumulative count of times the interface has been completely reset, often due to a physical layer event such as a cable disconnect or a faulty SFP module. A real-world scenario is when a loose Ethernet cable causes intermittent link drops, incrementing both 'carrier transitions' and 'interface resets' without necessarily causing CRC errors.

KKey Concepts to Remember

  • Read the scenario before looking for a memorised answer.
  • Find the constraint that changes the correct option.
  • Eliminate answers that are true in general but not in this case.

TExam Day Tips

  • Watch for words such as best, first, most likely and least administrative effort.
  • Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Real-world example

How this comes up in practice

A practitioner preparing for the 350-401 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.

What to study next

Got this wrong? Here's your next step.

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

Related practice questions

Related 350-401 practice-question pages

Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.

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FAQ

Questions learners often ask

What does this 350-401 question test?

Network Assurance — This question tests Network Assurance — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: Cable or hardware issue causing link flapping — Interface resets typically indicate that the interface has gone down and come back up, which is most commonly caused by a physical layer issue such as a faulty cable, damaged connector, or hardware problem that leads to link flapping. When the link flaps, the interface counters increment the 'resets' field, reflecting the number of times the interface has been reset due to a loss of carrier or a link state change. This is distinct from errors like CRC or collisions, which do not directly cause the interface to reset.

What should I do if I get this 350-401 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

Are there clue words in this question I should notice?

Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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Last reviewed: Jun 11, 2026

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