Question 116 of 1,819
Network Infrastructure and ConnectivitymediumDrag & DropObjective-mapped

Quick Answer

The correct answer is to verify VLAN assignment and switchport configuration as the second step in the OSI bottom-up troubleshooting order for client connectivity. This is correct because the bottom-up method starts with Layer 1 physical connectivity—checking cables and link lights—then moves to Layer 2, where VLAN membership and switchport settings ensure the data link layer can forward frames properly. On the CCNA 200-301 v2 exam, this drag-and-drop task tests your ability to apply the OSI model systematically, often with a trap where candidates jump to IP configuration (Layer 3) before confirming Layer 2 is sound. A common memory tip is to think “lights, VLANs, IPs, apps” to lock in the sequence: physical first, then data link, network, and finally application.

CCNA Network Infrastructure and Connectivity Practice Question

This 200-301 practice question tests your understanding of network infrastructure and connectivity. 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.

Drag and drop the following troubleshooting steps into the correct order to diagnose client connectivity using the OSI bottom-up method.

Question 1mediumdrag order
Full question →

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 physical cabling and link lights

Following the OSI bottom-up model, we begin with Layer 1 physical connectivity (cabling and link lights), then Layer 2 data link (VLAN and switchport configuration), Layer 3 network (IP configuration and default gateway), and finally Layer 7 application (DNS resolution and application settings).

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.

  • Check physical cabling and link lights

    Why this is correct

    This is correct because the OSI bottom-up method starts at Layer 1 (Physical). Checking cabling and link lights verifies the physical connection before moving up the stack.

    Related concept

    Access ports place end devices into a single VLAN.

  • Verify VLAN assignment and switchport configuration

    Why this is correct

    This is incorrect because verifying VLAN and switchport configuration belongs to Layer 2 (Data Link), which comes after Layer 1 in the bottom-up approach.

    Related concept

    Access ports place end devices into a single VLAN.

  • Test IP configuration and default gateway

    Why this is correct

    This is incorrect because testing IP configuration and default gateway is Layer 3 (Network), which should be checked after Layers 1 and 2 are verified.

    Related concept

    Access ports place end devices into a single VLAN.

  • Check DNS resolution and application settings

    Why this is correct

    This is incorrect because checking DNS and application settings is Layer 7 (Application), which is the highest layer and should be checked last in the bottom-up approach.

    Related concept

    Access ports place end devices into a single VLAN.

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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FAQ

Questions learners often ask

What does this 200-301 question test?

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

What is the correct answer to this question?

The correct answer is: Check physical cabling and link lights — Following the OSI bottom-up model, we begin with Layer 1 physical connectivity (cabling and link lights), then Layer 2 data link (VLAN and switchport configuration), Layer 3 network (IP configuration and default gateway), and finally Layer 7 application (DNS resolution and application settings).

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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Same concept, more angles

5 more ways this is tested on 200-301

These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.

Variation 1. Drag and drop the following troubleshooting steps into the correct order to diagnose a client connectivity issue using the OSI bottom-up method. The client cannot access a web server by its FQDN.

medium
  • A.Check physical connectivity (cables, link lights, interface status).
  • B.Verify DNS resolution (nslookup, DNS server reachability).
  • C.Check IP configuration (IP address, subnet mask, default gateway).
  • D.Verify MAC address table and VLAN configuration on the switch.

Why A: The bottom-up OSI approach starts with Layer 1 (physical) – step A; then Layer 2 (data link) – step D; then Layer 3 (network) – step C; and finally Layer 7 (application) – step B. This methodical progression isolates the issue layer by layer, ensuring all dependencies are checked systematically.

Variation 2. Drag and drop the following troubleshooting steps into the correct order to diagnose a client connectivity issue using the OSI bottom-up method.

medium
  • A.Check the physical cable connections and link lights
  • B.Verify IP address configuration and subnet mask
  • C.Ping the default gateway to test Layer 3 connectivity
  • D.Check the MAC address table on the switch

Why A: The OSI bottom-up troubleshooting method starts at Layer 1: first check physical cable connections and link lights (A). Next, at Layer 2, verify the switch's MAC address table (D) to ensure local segment communication is intact. Moving to Layer 3, confirm the IP address configuration and subnet mask (B) are correct. Finally, ping the default gateway (C) to validate end-to-end Layer 3 connectivity. The correct sequence is A → D → B → C, because each lower layer must function before higher-layer tests can succeed.

Variation 3. Drag and drop the following troubleshooting steps into the correct order to diagnose a client connectivity issue. Use the OSI bottom-up method, starting with the lowest layer and moving up.

medium
  • A.Check physical cabling and link lights, then verify IP configuration, then test application connectivity.
  • B.Test application connectivity, then verify IP configuration, then check physical cabling and link lights.
  • C.Verify IP configuration, then check physical cabling and link lights, then test application connectivity.
  • D.Check physical cabling and link lights, then test application connectivity, then verify IP configuration.

Why A: The bottom-up approach starts at Layer 1 and moves up to Layer 7, checking physical, network, and application layers in order.

Variation 4. Drag and drop the following troubleshooting steps into the correct order to diagnose a client connectivity issue using the OSI bottom-up method.

medium
  • A.Check physical connectivity (cables, link lights)
  • B.Verify IP configuration (DHCP, subnet mask)
  • C.Test DNS resolution (nslookup)
  • D.Ping the default gateway

Why A: The bottom-up approach starts at Layer 1 (physical connectivity), then moves to Layer 3 (IP configuration and gateway ping), and finally to Layer 7 (DNS resolution). No Layer 2 step is included in these steps. Verifying IP configuration, such as DHCP and subnet mask, is a Layer 3 activity, not Layer 2. This method ensures systematic isolation of the problem from the physical layer upward.

Variation 5. Drag and drop the following troubleshooting steps into the correct order to diagnose a client connectivity issue using the OSI bottom-up method.

medium
  • A.Check physical connectivity, then data link, then network, then transport, then application
  • B.Check application, then transport, then network, then data link, then physical
  • C.Check network, then data link, then physical, then transport, then application
  • D.Check physical, then network, then data link, then transport, then application

Why A: The OSI bottom-up method starts at physical layer and moves up. This ensures that lower-layer issues are resolved before higher-layer troubleshooting, preventing wasted effort on symptoms caused by underlying problems.

Last reviewed: Jun 6, 2026

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