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Read each scenario carefully and choose your answer before revealing the explanation. Then check why your choice was right or wrong. Repeat until the reasoning feels automatic.

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200-901 · topic practice

Troubleshooting practice questions

Practise Cisco DevNet Associate 200-901 Troubleshooting practice questions — original exam-style scenarios with answer choices, explanations, and analysis of common mistakes.

Courseiva uses original exam-style practice questions designed for learning and revision. The goal is to understand the concepts, recognise exam patterns, and improve through explanations — not memorise copied exam dumps.

Reviewed byJohnson Ajibi· MSc IT Security

14 questionsDomain: Troubleshooting

Practice 10 questions Browse domain →

What the exam tests

What to know about Troubleshooting

Troubleshooting questions test whether you can apply the concept in context, not just recognise a definition.

How the topic appears in realistic exam-style scenarios.

Which detail in the question changes the correct answer.

How to eliminate plausible but wrong options.

How to connect the question back to the wider exam objective.

Watch out for

Common Troubleshooting exam traps

▸Answering from memory before reading the full scenario.
▸Missing a constraint such as cost, availability, security, scope or command context.
▸Choosing a broad answer when the question asks for the most specific fix.
▸Ignoring why the wrong options are tempting.

Practice set

Troubleshooting questions

14 questions · select your answer, then reveal the explanation

Question 1easymultiple choice

Review the full routing breakdown →

A network engineer is troubleshooting connectivity issues and wants to verify the path that packets take from a source to a destination IP address. Which OSI layer is primarily responsible for packet forwarding and routing?

Trap 1: Layer 4 - Transport

Transport layer provides end-to-end communication and segmentation.

Trap 2: Layer 1 - Physical

Physical layer deals with bits and transmission media.

Trap 3: Layer 2 - Data Link

Data Link layer handles frames and MAC addresses within a single network segment.

Study all Troubleshooting common traps →

A
Layer 4 - Transport
Why wrong: Transport layer provides end-to-end communication and segmentation.
B
Layer 3 - Network
Network layer is responsible for packet forwarding, routing, and logical addressing.
C
Layer 1 - Physical
Why wrong: Physical layer deals with bits and transmission media.
D
Layer 2 - Data Link
Why wrong: Data Link layer handles frames and MAC addresses within a single network segment.

Full breakdown with real-world context →

Question 2hardmultiple choice

Review the full subnetting walkthrough →

An engineer is troubleshooting packet loss between two hosts on different subnets. The traceroute shows that packets reach the first hop router but then stop. The router's ARP table shows an incomplete entry for the next-hop IP address. What is the most likely cause?

Trap 1: The MTU is misconfigured on the outgoing interface.

MTU issues cause packet drops but not ARP incompleteness.

Trap 2: The routing protocol has not converged yet.

Routing convergence affects the route table, not ARP.

Trap 3: An ACL is blocking traffic on the outgoing interface.

ACLs drop packets after routing, they don't prevent ARP resolution.

Study all Troubleshooting common traps →

A
The MTU is misconfigured on the outgoing interface.
Why wrong: MTU issues cause packet drops but not ARP incompleteness.
B
The routing protocol has not converged yet.
Why wrong: Routing convergence affects the route table, not ARP.
C
The next-hop device is powered off or has a Layer 1 issue.
If the next-hop device is offline, the router cannot complete ARP.
D
An ACL is blocking traffic on the outgoing interface.
Why wrong: ACLs drop packets after routing, they don't prevent ARP resolution.

Full breakdown with real-world context →

Question 3easymultiple choice

Open the full VLAN trunking answer →

A network engineer is troubleshooting a connectivity issue between two hosts in different VLANs on the same switch. The hosts are in VLAN 10 and VLAN 20, respectively. The switch has an SVI for each VLAN and IP routing is enabled. Which command should be used to verify that the switch is forwarding traffic between the VLANs?

Trap 1: show interfaces trunk

Shows trunking status, not routing.

Trap 2: show vlan

Shows VLAN membership, not routing table.

Trap 3: show mac address-table

Shows MAC address table, not routing.

Study all Troubleshooting common traps →

A
show interfaces trunk
Why wrong: Shows trunking status, not routing.
B
show vlan
Why wrong: Shows VLAN membership, not routing table.
C
show ip route
Displays the routing table, confirming inter-VLAN routing.
D
show mac address-table
Why wrong: Shows MAC address table, not routing.

Full breakdown with real-world context →

Question 4mediummultiple choice

Read the full Troubleshooting explanation →

A developer is troubleshooting an HTTP API call that returns a 404 status code. Which of the following is the most likely cause?

Trap 1: The server is unavailable due to maintenance

That would typically result in a 503 Service Unavailable.

Trap 2: The server encountered an internal error

Internal errors generate 500 status.

Trap 3: The client lacks proper authentication

Authentication issues produce 401 Unauthorized.

Study all Troubleshooting common traps →

A
The server is unavailable due to maintenance
Why wrong: That would typically result in a 503 Service Unavailable.
B
The requested URL endpoint does not exist
404 Not Found means the server cannot find the requested resource.
C
The server encountered an internal error
Why wrong: Internal errors generate 500 status.
D
The client lacks proper authentication
Why wrong: Authentication issues produce 401 Unauthorized.

Full breakdown with real-world context →

Question 5mediummultiple choice

Open the full VLAN trunking answer →

An engineer is troubleshooting a connectivity issue between two devices on different VLANs. The switch connecting the devices is configured with 802.1Q trunking. At which OSI layer do VLANs operate?

Trap 1: Layer 4

Layer 4 deals with transport protocols like TCP and UDP.

Trap 2: Layer 1

Physical layer deals with bits, cables, and signals, not logical segmentation.

Trap 3: Layer 3

Layer 3 deals with routing and IP addressing, not VLANs.

Study all Troubleshooting common traps →

A
Layer 2
VLANs are a Layer 2 concept used to separate traffic on a switch.
B
Layer 4
Why wrong: Layer 4 deals with transport protocols like TCP and UDP.
C
Layer 1
Why wrong: Physical layer deals with bits, cables, and signals, not logical segmentation.
D
Layer 3
Why wrong: Layer 3 deals with routing and IP addressing, not VLANs.

Full breakdown with real-world context →

Question 6mediummulti select

Open the full VLAN trunking answer →

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.)

Trap 1: Ping the server's IP address from the switch management interface.

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

Trap 2: Ping the default gateway from a host in VLAN 100.

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

Trap 3: Check the MAC address table on the switch for the server's MAC.

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

Study all Troubleshooting common traps →

A
Ping the server's IP address from the switch management interface.
Why wrong: The switch management interface may be in a different VLAN, so this does not test the specific VLAN 100 path.
B
Ping the default gateway from a host in VLAN 100.
Why wrong: This checks Layer 3 connectivity but does not directly address the missing ARP entry for the server.
C
Check the ARP table on the default gateway router.
The hosts need to resolve the server's MAC, not the gateway's. The issue is on the switch or host side.
D
Check the MAC address table on the switch for the server's MAC.
Why wrong: The MAC address table shows Layer 2 paths, but the issue is ARP resolution which is Layer 3.
E
Verify that the switch port connected to the server is in VLAN 100.
If the server is on an access port in a different VLAN, the hosts in VLAN 100 cannot reach it.

Full breakdown with real-world context →

Question 7easymultiple choice

Review the full routing breakdown →

An engineer is troubleshooting a network issue and needs to verify the MAC address of the next-hop router on a directly connected segment. Which layer of the OSI model does the engineer need to examine to find this information?

Trap 1: Transport layer (Layer 4)

Layer 4 deals with TCP/UDP segments and ports.

Trap 2: Physical layer (Layer 1)

Layer 1 deals with bits, cables, and hubs, not MAC addresses.

Trap 3: Network layer (Layer 3)

Layer 3 uses IP addresses, not MAC addresses.

Study all Troubleshooting common traps →

A
Data Link layer (Layer 2)
MAC addresses are used at Layer 2 for local network communication.
B
Transport layer (Layer 4)
Why wrong: Layer 4 deals with TCP/UDP segments and ports.
C
Physical layer (Layer 1)
Why wrong: Layer 1 deals with bits, cables, and hubs, not MAC addresses.
D
Network layer (Layer 3)
Why wrong: Layer 3 uses IP addresses, not MAC addresses.

Full breakdown with real-world context →

Question 8hardmulti select

Read the full Troubleshooting explanation →

A network automation script using NX-API on a Nexus switch fails intermittently with HTTP 500 errors. Which two troubleshooting steps are most effective in diagnosing the issue? (Choose two.)

Trap 1: Check the length of the JSON payload sent to the API.

Payload size limits cause 413 errors, not 500.

Trap 2: Ensure the switch is running NX-OS version 9.3(1) or later.

Version is less likely to cause intermittent 500 errors.

Trap 3: Use HTTP instead of HTTPS for the API requests.

Using HTTP does not fix the issue and introduces security risks.

Study all Troubleshooting common traps →

A
Check the length of the JSON payload sent to the API.
Why wrong: Payload size limits cause 413 errors, not 500.
B
Ensure the switch is running NX-OS version 9.3(1) or later.
Why wrong: Version is less likely to cause intermittent 500 errors.
C
Enable NX-API debugging on the switch to capture detailed logs.
Debug logs help identify the exact failure point.
D
Verify that the NX-API sandbox feature is enabled and running.
If NX-API is not fully enabled, it can lead to intermittent errors.
E
Use HTTP instead of HTTPS for the API requests.
Why wrong: Using HTTP does not fix the issue and introduces security risks.

Full breakdown with real-world context →

Question 9easymultiple choice

Review the full subnetting walkthrough →

You are troubleshooting connectivity for a remote branch office. The branch router (BR) connects to the head office router (HQ) via a point-to-point T1 link. The HQ router is also connected to the internet via a separate interface. Users at the branch can access the internet but cannot reach servers at the head office (subnet 10.10.10.0/24). You run 'show ip route' on BR and see a default route pointing to HQ's IP address, but no specific route for 10.10.10.0/24. The HQ router has a connected route for that subnet. On HQ, you see that the interface towards BR is up/up, and you can ping the BR's interface IP. What is the most likely cause of the issue?

Trap 1: An ACL on the HQ router is blocking traffic from the branch subnet.

There is no indication of ACL blocks; the issue is more fundamental.

Trap 2: The default route on BR is not pointing to the correct next-hop.

If internet works, the default route is correct for outgoing traffic.

Trap 3: The T1 link is experiencing errors causing packet loss.

Internet connectivity works, so the link is functional.

Study all Troubleshooting common traps →

A
The HQ router does not have a route for the branch's local subnet.
Without a return route, traffic from branch to HQ can leave but replies are dropped.
B
An ACL on the HQ router is blocking traffic from the branch subnet.
Why wrong: There is no indication of ACL blocks; the issue is more fundamental.
C
The default route on BR is not pointing to the correct next-hop.
Why wrong: If internet works, the default route is correct for outgoing traffic.
D
The T1 link is experiencing errors causing packet loss.
Why wrong: Internet connectivity works, so the link is functional.

Full breakdown with real-world context →

Question 10hardmultiple choice

Read the full Troubleshooting explanation →

A network engineer is troubleshooting a Kubernetes deployment where pods are failing to start with the error 'CrashLoopBackOff'. The pod log shows 'bind: address already in use'. The deployment runs multiple replicas of a container that listens on port 8080. What is the most likely cause?

Trap 1: The container is attempting to bind to a privileged port without…

Port 8080 is not privileged (privileged ports are below 1024).

Trap 2: The service is using NodePort and the node port is already in use.

NodePort is a service type; the error occurs at the container level, not the service level.

Trap 3: Multiple containers in the same pod are trying to bind to the same…

Containers in a pod share the same network namespace; they cannot bind to the same port, but the error would occur at pod creation, not as CrashLoopBackOff after start.

Study all Troubleshooting common traps →

A
The container is attempting to bind to a privileged port without the necessary capabilities.
Why wrong: Port 8080 is not privileged (privileged ports are below 1024).
B
The deployment has hostPort: 8080 specified, causing port conflict when multiple replicas are scheduled on the same node.
hostPort reserves the port on the host node, so only one pod per node can use it. With multiple replicas, subsequent pods fail with address in use.
C
The service is using NodePort and the node port is already in use.
Why wrong: NodePort is a service type; the error occurs at the container level, not the service level.
D
Multiple containers in the same pod are trying to bind to the same port.
Why wrong: Containers in a pod share the same network namespace; they cannot bind to the same port, but the error would occur at pod creation, not as CrashLoopBackOff after start.

Full breakdown with real-world context →

Question 11hardmultiple choice

Study the full Python automation breakdown →

A developer is troubleshooting a CI/CD pipeline that automatically deploys configuration changes to network devices. The pipeline includes a stage that runs Python unit tests. Which of the following would be a valid test to include in that stage to validate the configuration before deployment?

Trap 1: Test that the configuration can be applied to the device by sending…

This requires network access (NETCONF) to test, which is not suitable for a unit test stage; unit tests should be isolated and fast.

Trap 2: Test that the configuration changes do not break connectivity by…

This test requires network connectivity and is performed after deployment, so it is not a unit test and cannot be run before deployment.

Trap 3: Test that the configuration adheres to company naming conventions…

Testing naming conventions with a regex is a form of policy validation, but it is not a unit test of the configuration's format; it is more of a linter check and could be combined with unit tests, but the primary unit test is to validate the file format.

Study all Troubleshooting common traps →

A
Test that the configuration can be applied to the device by sending it via NETCONF
Why wrong: This requires network access (NETCONF) to test, which is not suitable for a unit test stage; unit tests should be isolated and fast.
B
Test that the configuration file is valid JSON
Correct. Validating that the configuration file is valid JSON is a fast, isolated unit test that catches syntax errors before deployment.
C
Test that the configuration changes do not break connectivity by pinging the device after deployment
Why wrong: This test requires network connectivity and is performed after deployment, so it is not a unit test and cannot be run before deployment.
D
Test that the configuration adheres to company naming conventions using a regular expression
Why wrong: Testing naming conventions with a regex is a form of policy validation, but it is not a unit test of the configuration's format; it is more of a linter check and could be combined with unit tests, but the primary unit test is to validate the file format.

Full breakdown with real-world context →

Question 12mediummulti select

Read the full REST/YANG explanation →

A developer is troubleshooting a Cisco RESTCONF API call that returns a 409 Conflict error. Which two scenarios could cause this? (Choose two.)

Trap 1: Authentication token is missing.

Missing token results in 401 Unauthorized.

Trap 2: The resource does not exist.

A missing resource would give 404, not 409.

Trap 3: The request contains invalid data types.

Invalid data types result in 400 Bad Request.

Study all Troubleshooting common traps →

A
Authentication token is missing.
Why wrong: Missing token results in 401 Unauthorized.
B
The resource's current state conflicts with the requested change (e.g., trying to delete a resource that is in use).
State conflicts, like deleting a resource that is referenced, cause 409.
C
The resource already exists and the request attempts to create a duplicate.
Creating a duplicate resource is a typical cause of 409.
D
The resource does not exist.
Why wrong: A missing resource would give 404, not 409.
E
The request contains invalid data types.
Why wrong: Invalid data types result in 400 Bad Request.

Full breakdown with real-world context →

Question 13mediumdrag order

Read the full Troubleshooting explanation →

Drag and drop the steps to troubleshoot a network connectivity issue using the OSI model from bottom to top.

Drag steps to the numbered slots on the right, or tap a step then tap a slot.

Steps

Order

1Step 1

2Step 2

3Step 3

4Step 4

5Step 5

Trap 1: Check application layer, then transport layer, then network layer,…

This is a top-down approach, which is not from bottom to top as required. It starts with higher layers, missing lower-layer issues first.

Trap 2: Check physical cables and interfaces, then verify network layer,…

This skips the data link layer, which is crucial for verifying MAC addressing and switching. Missing a layer can lead to incomplete troubleshooting.

Trap 3: Check network layer first, then physical cables and interfaces,…

This starts with network layer instead of physical, which is out of order. Physical layer issues must be ruled out first in bottom-up troubleshooting.

Study all Troubleshooting common traps →

A
Check physical cables and interfaces, then verify data link layer, then verify network layer, then verify transport layer, then verify application layer.
This follows the OSI model from bottom to top (Physical to Application), systematically isolating issues layer by layer.
B
Check application layer, then transport layer, then network layer, then data link layer, then physical layer.
Why wrong: This is a top-down approach, which is not from bottom to top as required. It starts with higher layers, missing lower-layer issues first.
C
Check physical cables and interfaces, then verify network layer, then verify transport layer, then verify application layer, skipping data link layer.
Why wrong: This skips the data link layer, which is crucial for verifying MAC addressing and switching. Missing a layer can lead to incomplete troubleshooting.
D
Check network layer first, then physical cables and interfaces, then data link layer, then transport layer, then application layer.
Why wrong: This starts with network layer instead of physical, which is out of order. Physical layer issues must be ruled out first in bottom-up troubleshooting.

Full breakdown with real-world context →

Question 14hardmulti select

Read the full Troubleshooting explanation →

An engineer is troubleshooting a network issue where a client cannot reach a server. The client uses HTTPS. Which TWO factors are essential for a successful TLS handshake?

Trap 1: The handshake uses UDP for faster negotiation

TLS typically runs over TCP.

Trap 2: The client must present a certificate to the server

Client certificates are optional, not required for a basic TLS handshake.

Trap 3: The client must have a public key to encrypt the session

The client uses the server's public key (from certificate) to encrypt the pre-master secret.

Study all Troubleshooting common traps →

A
The server must have a valid digital certificate
The certificate proves the server's identity.
B
The handshake uses UDP for faster negotiation
Why wrong: TLS typically runs over TCP.
C
The client must present a certificate to the server
Why wrong: Client certificates are optional, not required for a basic TLS handshake.
D
The client must have a public key to encrypt the session
Why wrong: The client uses the server's public key (from certificate) to encrypt the pre-master secret.
E
The server's private key is used to decrypt the pre-master secret
Only the server's private key can decrypt the pre-master secret.

Full breakdown with real-world context →

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Frequently asked questions

What does the 200-901 exam test about Troubleshooting?: Troubleshooting questions test whether you can apply the concept in context, not just recognise a definition.
How should I use these practice questions?: Select your answer before revealing the explanation. Then read why each option is right or wrong — this active recall approach builds retention far faster than re-reading notes.
Can I practise just Troubleshooting questions in a focused session?: Yes — the session launcher on this page draws every question from the Troubleshooting domain. Use a 10-question session first to gauge your baseline, then move to 20 or 30 once the weak spots are clear.
Where can I practise other 200-901 topics?: Use the topic links above to move to related areas, or go back to the 200-901 question bank to see all topics.
Are these real exam questions or dumps?: These are original practice questions written to test the same concepts the 200-901 exam covers. They are not copied from any real exam or dump site.

Troubleshooting only

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Mixed 200-901 session

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A free account saves results across sessions and highlights which topics need work.

Study resources

All 200-901 questions Troubleshooting domain overview 200-901 exam guide

Exam traps to avoid

▸Answering from memory before reading the full scenario.
▸Missing a constraint such as cost, availability, security, scope or command context.
▸Choosing a broad answer when the question asks for the most specific fix.
▸Ignoring why the wrong options are tempting.

Troubleshooting practice questions

What to know about Troubleshooting

Common Troubleshooting exam traps

Troubleshooting questions

A network engineer is troubleshooting connectivity issues and wants to verify the path that packets take from a source to a destination IP address. Which OSI layer is primarily responsible for packet forwarding and routing?

An engineer is troubleshooting packet loss between two hosts on different subnets. The traceroute shows that packets reach the first hop router but then stop. The router's ARP table shows an incomplete entry for the next-hop IP address. What is the most likely cause?

A developer is troubleshooting an HTTP API call that returns a 404 status code. Which of the following is the most likely cause?

An engineer is troubleshooting a connectivity issue between two devices on different VLANs. The switch connecting the devices is configured with 802.1Q trunking. At which OSI layer do VLANs operate?

An engineer is troubleshooting a network issue and needs to verify the MAC address of the next-hop router on a directly connected segment. Which layer of the OSI model does the engineer need to examine to find this information?

A network automation script using NX-API on a Nexus switch fails intermittently with HTTP 500 errors. Which two troubleshooting steps are most effective in diagnosing the issue? (Choose two.)

A network engineer is troubleshooting a Kubernetes deployment where pods are failing to start with the error 'CrashLoopBackOff'. The pod log shows 'bind: address already in use'. The deployment runs multiple replicas of a container that listens on port 8080. What is the most likely cause?

A developer is troubleshooting a CI/CD pipeline that automatically deploys configuration changes to network devices. The pipeline includes a stage that runs Python unit tests. Which of the following would be a valid test to include in that stage to validate the configuration before deployment?

A developer is troubleshooting a Cisco RESTCONF API call that returns a 409 Conflict error. Which two scenarios could cause this? (Choose two.)

Drag and drop the steps to troubleshoot a network connectivity issue using the OSI model from bottom to top.

An engineer is troubleshooting a network issue where a client cannot reach a server. The client uses HTTPS. Which TWO factors are essential for a successful TLS handshake?

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Frequently asked questions

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Study resources

Exam traps to avoid