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 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?
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 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
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.
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 DHCP server is unreachable
Why this is correct
APIPA addresses are assigned when DHCP fails, so the DHCP server is unreachable.
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 default gateway is misconfigured
Why it's wrong here
A misconfigured default gateway would not cause an APIPA address; the client would still get a valid IP from DHCP.
✗
The DNS server is down
Why it's wrong here
A DNS issue would not affect IP address assignment; APIPA is unrelated to DNS.
✗
The file server is offline
Why it's wrong here
The file server being offline would not cause the client to have an APIPA address; the client would still have a valid IP.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse APIPA with a DNS or gateway issue, but APIPA specifically indicates a DHCP failure, and local subnet connectivity does not require a gateway or DNS to function.
Detailed technical explanation
How to think about this question
APIPA is defined in RFC 3927 and uses a link-local address block (169.254.0.0/16) with a subnet mask of 255.255.0.0. The client performs Duplicate Address Detection (DAD) via ARP probes before assigning the address, and it will continue to attempt DHCP discovery every 5 minutes. In a real-world scenario, a faulty switch port or VLAN mismatch could cause the DHCP DISCOVER broadcast to never reach the DHCP server, resulting in APIPA even if the server is 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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this N10-009 question in full detail.
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 — 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.
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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Question Discussion
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