- A
Check the DNS server configuration.
Why wrong: The workstation does not have a valid IP address, so DNS is not yet a factor. The issue is with IP address assignment.
- B
Replace the network cable between the wall jack and the workstation.
Why wrong: The link light is green, indicating a good physical connection. Cable replacement is unlikely to resolve the issue.
- C
Check the switch port configuration for security features such as DHCP snooping or port security.
Security features on the switch port may be blocking DHCP discovery messages or responses, causing the workstation to receive no offer and fall back to APIPA. This is the most logical next step.
- D
Verify the default gateway setting on the workstation.
Why wrong: The default gateway cannot be reached because the workstation does not have a valid IP address. The root cause is the missing DHCP lease.
Quick Answer
The correct next step is to check the switch port configuration for security features such as DHCP snooping or port security. A 169.254.x.x APIPA address indicates the workstation failed to obtain a DHCP lease, and since the DHCP server is operational with available addresses, the problem must be upstream at the access layer. Switch port security can limit the number of MAC addresses or block DHCP traffic entirely, while DHCP snooping filters untrusted DHCP messages—both can silently prevent a lease without disabling the link light. On the CompTIA Network+ N10-009 exam, this scenario tests your ability to distinguish between server-side and infrastructure-side DHCP failures; a common trap is assuming the DHCP server itself is the culprit when it’s actually a switch-level restriction. Memory tip: APIPA means “Ask Port—Is Port Access blocked?”—always verify the switch port’s security settings before blaming the server.
N10-009 Network Troubleshooting Practice Question
This N10-009 practice question tests your understanding of network troubleshooting. 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 user reports that their workstation cannot connect to the network. The technician checks the IP configuration and sees that the workstation has an IP address of 169.254.25.110. The DHCP server is operational and has available addresses. The switch port connected to the workstation shows a solid green link light. What should the technician check NEXT?
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 switch port configuration for security features such as DHCP snooping or port security.
The workstation has an APIPA address (169.254.x.x), which indicates it failed to obtain a DHCP lease. Since the DHCP server is operational and has available addresses, the issue likely lies with the switch port configuration. Security features such as DHCP snooping or port security can block DHCP traffic or limit the number of MAC addresses, preventing the workstation from receiving a valid IP address. Checking the switch port configuration is the logical next step.
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.
- ✗
Check the DNS server configuration.
Why it's wrong here
The workstation does not have a valid IP address, so DNS is not yet a factor. The issue is with IP address assignment.
- ✗
Replace the network cable between the wall jack and the workstation.
Why it's wrong here
The link light is green, indicating a good physical connection. Cable replacement is unlikely to resolve the issue.
- ✓
Check the switch port configuration for security features such as DHCP snooping or port security.
Why this is correct
Security features on the switch port may be blocking DHCP discovery messages or responses, causing the workstation to receive no offer and fall back to APIPA. This is the most logical next step.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Verify the default gateway setting on the workstation.
Why it's wrong here
The default gateway cannot be reached because the workstation does not have a valid IP address. The root cause is the missing DHCP lease.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume a link light guarantees full connectivity and jump to DNS or gateway issues, but Cisco tests the understanding that APIPA addresses specifically indicate DHCP failure, and the next step is to investigate Layer 2 security features that could block DHCP traffic.
Detailed technical explanation
How to think about this question
DHCP snooping is a security feature that filters DHCP messages on untrusted ports, typically blocking DHCPOFFER and DHCPACK packets from unauthorized servers. If the switch port is configured as untrusted and the DHCP server is on a different VLAN, the DHCP replies may be dropped. Port security can also limit the number of MAC addresses per port; if the limit is exceeded, the port may err-disable or drop frames, preventing DHCP discovery. The APIPA address (169.254.0.0/16) is automatically assigned by the OS when no DHCP response is received after multiple retries (RFC 3927).
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 N10-009 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.
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FAQ
Questions learners often ask
What does this N10-009 question test?
Network Troubleshooting — This question tests Network Troubleshooting — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Check the switch port configuration for security features such as DHCP snooping or port security. — The workstation has an APIPA address (169.254.x.x), which indicates it failed to obtain a DHCP lease. Since the DHCP server is operational and has available addresses, the issue likely lies with the switch port configuration. Security features such as DHCP snooping or port security can block DHCP traffic or limit the number of MAC addresses, preventing the workstation from receiving a valid IP address. Checking the switch port configuration is the logical next step.
What should I do if I get this N10-009 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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
1 more ways this is tested on N10-009
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. A user reports that they cannot connect to a file server on the same subnet. The technician checks the IP configuration and sees an IP address of 169.254.5.10. What is the most likely cause?
easy- ✓ A.The DHCP server is unreachable
- B.The default gateway is misconfigured
- C.The DNS server is down
- D.The file server is offline
Why A: The IP address 169.254.5.10 is an Automatic Private IP Addressing (APIPA) address from the 169.254.0.0/16 range, which Windows assigns when a DHCP client fails to obtain a lease from a DHCP server. Since the user is on the same subnet as the file server, a missing default gateway or DNS server would not prevent local connectivity, but the inability to reach the DHCP server indicates a broader network issue that also prevents the client from obtaining a valid IP address.
Last reviewed: Jun 11, 2026
This N10-009 practice question is part of Courseiva's free CompTIA 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 N10-009 exam.
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