Question 983 of 1,819
AI and Network OperationsmediumTroubleshootingObjective-mapped

Quick Answer

The answer is an incomplete ARP entry for the next-hop IP 192.168.1.1, which reveals a Layer 2 connectivity issue as the root cause of the intermittent host-to-server problem. This is correct because even when the routing table contains a valid default route toward the server at 10.0.0.100, the router cannot forward packets if the ARP cache fails to resolve the next-hop MAC address—an incomplete entry means no ARP reply was received, breaking the data link. On the CCNA 200-301 v2 exam, this scenario tests your ability to correlate routing table output with ARP cache status and interface states, a common troubleshooting sequence for intermittent connectivity. A frequent trap is assuming a missing route is the culprit when the route exists but the ARP resolution has failed, often due to a misconfigured switchport or a flapping link. Remember the mnemonic "RIA" for your diagnostic flow: Route, Incomplete ARP, Interface—check the route first, then the ARP entry, then the interface status to isolate the layer where the break occurs.

CCNA AI and Network Operations Practice Question

This 200-301 practice question tests your understanding of ai and network operations. 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.

Network Topology
G0/0192.168.10.1/24G0/110.0.0.1/30G0/010.0.0.2/30linkG0/010.0.0.2/3010.0.0.100linkHostsVLAN 10R1R2Server

You are connected to R1 via the console. R1 is a Cisco ISR 4321 router running IOS-XE 17.3. The network team has reported intermittent connectivity issues between VLAN 10 hosts and the server at 10.0.0.100. You suspect a routing problem and need to analyze the IP routing table, ARP cache, and interface status to identify the cause. Use the provided outputs to diagnose the issue.

Question 1mediumTroubleshooting
Open the full VLAN trunking answer →

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

The routing table shows a default route via 192.168.1.1, but the ARP cache has an incomplete entry for that next-hop IP, indicating a Layer 2 connectivity issue.

The issue is likely a missing or incorrect route, an incomplete ARP entry, or an interface problem. By checking the routing table, you can confirm if a route to 10.0.0.100 exists. The ARP cache shows whether the next-hop MAC is learned. Interface status indicates if the link is operational. The solution commands reveal these details, allowing you to pinpoint the cause (e.g., default route missing, ARP timeout, or interface down).

Key principle: A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.

Answer analysis

Option-by-option breakdown

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

  • The routing table shows a default route via 192.168.1.1, but the ARP cache has an incomplete entry for that next-hop IP, indicating a Layer 2 connectivity issue.

    Why this is correct

    This is correct because an incomplete ARP entry for the next-hop router means the router cannot resolve the MAC address, preventing packet forwarding. This is a common cause of intermittent connectivity.

    Related concept

    Access ports place end devices into a single VLAN.

  • The routing table has a static route to 10.0.0.0/24 via 192.168.1.2, but the interface GigabitEthernet0/0/0 is administratively down.

    Why it's wrong here

    This is incorrect because an administratively down interface would cause a complete loss of connectivity, not intermittent issues. The question states intermittent problems, so this is too severe.

  • The routing table shows a route to 10.0.0.0/16 via 192.168.1.1, but the ARP cache has a complete entry for 192.168.1.1, indicating the issue is at Layer 3.

    Why it's wrong here

    This is incorrect because a complete ARP entry means Layer 2 resolution is successful, so the problem is not at Layer 2. The route exists, so routing should work unless there is a firewall or ACL issue.

  • The routing table has no route to 10.0.0.100, and the ARP cache is empty for all entries, indicating a complete routing failure.

    Why it's wrong here

    This is incorrect because a missing route would cause a total failure to reach the server, not intermittent connectivity. The question specifies intermittent issues, so a missing route is too absolute.

Option-by-option analysis

Why each answer is right or wrong

Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.

The routing table shows a default route via 192.168.1.1, but the ARP cache has an incomplete entry for that next-hop IP, indicating a Layer 2 connectivity issue.Correct answer

Why this is correct

This is correct because an incomplete ARP entry for the next-hop router means the router cannot resolve the MAC address, preventing packet forwarding. This is a common cause of intermittent connectivity.

The routing table has a static route to 10.0.0.0/24 via 192.168.1.2, but the interface GigabitEthernet0/0/0 is administratively down.Wrong answer — click to see why

Why this is wrong here

The specific factual error is that an administratively down interface results in a hard failure, not intermittent connectivity.

Why candidates choose this

Candidates might pick this because they know interface status affects routing, but they overlook the 'intermittent' clue.

The routing table shows a route to 10.0.0.0/16 via 192.168.1.1, but the ARP cache has a complete entry for 192.168.1.1, indicating the issue is at Layer 3.Wrong answer — click to see why

Why this is wrong here

The specific factual error is that a complete ARP entry indicates no Layer 2 problem, contradicting the symptom of intermittent connectivity.

Why candidates choose this

Candidates might pick this because they focus on routing table entries but ignore that ARP completeness suggests the path is functional.

The routing table has no route to 10.0.0.100, and the ARP cache is empty for all entries, indicating a complete routing failure.Wrong answer — click to see why

Why this is wrong here

The specific factual error is that a missing route results in consistent unreachability, not intermittent problems.

Why candidates choose this

Candidates might pick this because they assume routing table absence is the only cause, but they miss the 'intermittent' qualifier.

Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”

Common exam traps

Common exam trap: an active trunk can still block the VLAN you need

A trunk being up does not prove every VLAN is crossing it. Check allowed VLAN lists, native VLAN mismatch, VLAN existence and access-port assignment.

Detailed technical explanation

How to think about this question

VLAN questions usually combine access-port and trunking clues. The key is to identify whether the issue is local to one switchport, caused by the trunk, or caused by the VLAN not existing where it needs to exist.

KKey Concepts to Remember

  • Access ports place end devices into a single VLAN.
  • Trunk ports carry multiple VLANs between switches.
  • Allowed VLAN lists decide which VLANs can cross a trunk.
  • Native VLAN mismatch can create confusing symptoms.

TExam Day Tips

  • Use show vlan brief to verify access VLANs.
  • Use show interfaces trunk to verify trunk state and allowed VLANs.
  • Do not treat every same-VLAN issue as a routing problem.

Key takeaway

A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.

Real-world example

How this comes up in practice

A help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.

What to study next

Got this wrong? Here's your next step.

Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related 200-301 questions on switching, trunking, and access-port configuration.

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Related 200-301 practice-question pages

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FAQ

Questions learners often ask

What does this 200-301 question test?

AI and Network Operations — This question tests AI and Network Operations — Access ports place end devices into a single VLAN..

What is the correct answer to this question?

The correct answer is: The routing table shows a default route via 192.168.1.1, but the ARP cache has an incomplete entry for that next-hop IP, indicating a Layer 2 connectivity issue. — The issue is likely a missing or incorrect route, an incomplete ARP entry, or an interface problem. By checking the routing table, you can confirm if a route to 10.0.0.100 exists. The ARP cache shows whether the next-hop MAC is learned. Interface status indicates if the link is operational. The solution commands reveal these details, allowing you to pinpoint the cause (e.g., default route missing, ARP timeout, or interface down).

What should I do if I get this 200-301 question wrong?

Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related 200-301 questions on switching, trunking, and access-port configuration.

What is the key concept behind this question?

Access ports place end devices into a single VLAN.

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Last reviewed: Jun 7, 2026

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This 200-301 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 200-301 exam.