Question 249 of 505
Network FundamentalsmediumMultiple SelectObjective-mapped

Quick Answer

The answer is to verify that the switch port connected to the server is in VLAN 100. This is correct because when the ARP table is missing the server MAC address, it indicates the switch cannot learn the server’s Layer 2 address through normal broadcast flooding within VLAN 100; if the server port is assigned to a different VLAN, it resides in a separate broadcast domain and will never receive ARP requests from hosts in VLAN 100, so the switch never records its MAC. On the Cisco DevNet Associate 200-901 exam, this scenario tests your understanding of VLAN segmentation and Layer 2 forwarding—a common trap is to immediately suspect IP misconfiguration or a faulty cable, when the root cause is often a simple port VLAN mismatch. A reliable memory tip is “ARP learns by broadcast, broadcast stays in VLAN”—if the server’s port isn’t in the same VLAN, the switch can’t populate its ARP table for that server.

200-901 Network Fundamentals Practice Question

This 200-901 practice question tests your understanding of network fundamentals. 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.

A network engineer is troubleshooting an issue where hosts in VLAN 100 cannot reach a server at 10.1.1.100. The switch interfaces are configured as access ports in VLAN 100, and the default gateway is 10.1.1.1. The engineer checks the switch and finds that the ARP table does not contain the server's MAC address. Which two actions should the engineer take to resolve the issue? (Choose two.)

Question 1mediummulti select
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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

Check the ARP table on the default gateway router.

Option E is correct because if the switch port connected to the server is not in VLAN 100, the server will be in a different broadcast domain and will not receive ARP requests from hosts in VLAN 100. This would cause the ARP table on the switch to lack the server's MAC address, as the switch cannot learn it through normal Layer 2 flooding within the VLAN.

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.

  • Ping the server's IP address from the switch management interface.

    Why it's wrong here

    The switch management interface may be in a different VLAN, so this does not test the specific VLAN 100 path.

  • Ping the default gateway from a host in VLAN 100.

    Why it's wrong here

    This checks Layer 3 connectivity but does not directly address the missing ARP entry for the server.

  • Check the ARP table on the default gateway router.

    Why this is correct

    The hosts need to resolve the server's MAC, not the gateway's. The issue is on the switch or host side.

    Related concept

    Read the scenario before looking for a memorised answer.

  • Check the MAC address table on the switch for the server's MAC.

    Why it's wrong here

    The MAC address table shows Layer 2 paths, but the issue is ARP resolution which is Layer 3.

  • Verify that the switch port connected to the server is in VLAN 100.

    Why this is correct

    If the server is on an access port in a different VLAN, the hosts in VLAN 100 cannot reach it.

    Related concept

    Read the scenario before looking for a memorised answer.

Common exam traps

Common exam trap: answer the scenario, not the keyword

Cisco often tests the distinction between the MAC address table (Layer 2 forwarding) and the ARP table (Layer 3 resolution), leading candidates to incorrectly choose checking the MAC address table when the real issue is VLAN membership affecting ARP propagation.

Trap categories for this question

  • Command / output trap

    The MAC address table shows Layer 2 paths, but the issue is ARP resolution which is Layer 3.

Detailed technical explanation

How to think about this question

ARP operates at Layer 2/3 boundary: a host sends an ARP request broadcast to resolve an IP to a MAC within its VLAN. If the server is in a different VLAN (e.g., due to a misconfigured access port), the broadcast never reaches it, so no ARP reply is received, and the switch's ARP cache remains empty. In real-world scenarios, this often occurs after a VLAN change on a port without reconnecting the cable or after a trunk misconfiguration.

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 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.

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

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FAQ

Questions learners often ask

What does this 200-901 question test?

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

What is the correct answer to this question?

The correct answer is: Check the ARP table on the default gateway router. — Option E is correct because if the switch port connected to the server is not in VLAN 100, the server will be in a different broadcast domain and will not receive ARP requests from hosts in VLAN 100. This would cause the ARP table on the switch to lack the server's MAC address, as the switch cannot learn it through normal Layer 2 flooding within the VLAN.

What should I do if I get this 200-901 question wrong?

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

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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