- A
The workstation's network cable is unplugged.
Why wrong: If the cable were unplugged, the network interface would likely show 'Network cable unplugged' or a disconnected status, and ipconfig would not show an APIPA address (it would show no IP or a loopback).
- B
The DNS server is not responding.
Why wrong: DNS issues would result in name resolution failures, but the workstation would still have a valid IP address from DHCP or static config. APIPA indicates a DHCP failure.
- C
The DHCP server is unreachable or not functioning.
APIPA addresses are assigned when a DHCP client cannot communicate with a DHCP server. This is the most likely cause.
- D
The workstation has been assigned a static IP address in the wrong subnet.
Why wrong: A static IP assignment would not result in an APIPA address. APIPA is self-assigned automatically only when DHCP fails.
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 they cannot access any network resources. The technician runs 'ipconfig' on the workstation and sees that the IP address is 169.254.23.45 with a subnet mask of 255.255.0.0. What is the most likely cause of this issue?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"most likely"Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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 DHCP server is unreachable or not functioning.
The IP address 169.254.23.45 with a subnet mask of 255.255.0.0 is an Automatic Private IP Addressing (APIPA) address, which is assigned by the operating system when a DHCP discovery attempt fails. This indicates that the workstation was unable to contact a DHCP server to obtain a valid IP configuration, making an unreachable or non-functioning DHCP server the most likely cause.
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.
- ✗
The workstation's network cable is unplugged.
Why it's wrong here
If the cable were unplugged, the network interface would likely show 'Network cable unplugged' or a disconnected status, and ipconfig would not show an APIPA address (it would show no IP or a loopback).
- ✗
The DNS server is not responding.
- ✓
The DHCP server is unreachable or not functioning.
Why this is correct
APIPA addresses are assigned when a DHCP client cannot communicate with a DHCP server. This is the most likely cause.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The workstation has been assigned a static IP address in the wrong subnet.
Why it's wrong here
A static IP assignment would not result in an APIPA address. APIPA is self-assigned automatically only when DHCP fails.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse APIPA with a physical connectivity issue, but APIPA specifically indicates that the DHCP process failed, not necessarily that the cable is unplugged.
Trap categories for this question
Command / output trap
If the cable were unplugged, the network interface would likely show 'Network cable unplugged' or a disconnected status, and ipconfig would not show an APIPA address (it would show no IP or a loopback).
Detailed technical explanation
How to think about this question
APIPA is defined in RFC 3927 and uses the 169.254.0.0/16 range; the workstation performs a gratuitous ARP probe to ensure no other host uses the same link-local address before assigning it. In a real-world scenario, a misconfigured DHCP relay agent or a VLAN mismatch can cause DHCP discover broadcasts to never reach the server, resulting in APIPA even if the DHCP server is actually operational.
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 network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.
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: The DHCP server is unreachable or not functioning. — The IP address 169.254.23.45 with a subnet mask of 255.255.0.0 is an Automatic Private IP Addressing (APIPA) address, which is assigned by the operating system when a DHCP discovery attempt fails. This indicates that the workstation was unable to contact a DHCP server to obtain a valid IP configuration, making an unreachable or non-functioning DHCP server the most likely cause.
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.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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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