N10-009 Practice Question: APIPA addresses are in the 169.254.0.0/16 range.
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. A key principle to apply: aPIPA addresses are in the 169.254.0.0/16 range.. 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 checks the IP configuration and sees that the workstation has an IP address of 169.254.1.5. 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 unavailable
The IP address 169.254.1.5 is an Automatic Private IP Addressing (APIPA) address (169.254.0.0/16 range), which Windows assigns when a DHCP client fails to receive a lease from a DHCP server. Since the workstation cannot obtain a valid IP configuration, it cannot communicate with any network resources, confirming that the DHCP server is unavailable.
Key principle: APIPA addresses are in the 169.254.0.0/16 range.
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 DNS server is down
Why it's wrong here
A DNS failure would not prevent the workstation from obtaining an IP address.
✓
The DHCP server is unavailable
Why this is correct
An APIPA address indicates DHCP failure, so the DHCP server is likely unreachable.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
APIPA addresses are in the 169.254.0.0/16 range.
✗
The default gateway is incorrect
Why it's wrong here
An incorrect gateway would allow the workstation to get a valid IP, but APIPA appears only when DHCP fails.
✗
The subnet mask is mismatched
Why it's wrong here
A subnet mask mismatch would still allow a valid DHCP lease to be obtained; APIPA occurs only when no lease is obtained.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may confuse APIPA with a static IP misconfiguration or assume a DNS issue, but the 169.254.x.x address is a definitive indicator of DHCP failure, not a gateway or subnet problem.
Detailed technical explanation
How to think about this question
APIPA is defined in RFC 3927 and uses the 169.254.0.0/16 link-local block, with the client performing Duplicate Address Detection (DAD) via ARP probes before assigning the address. In a production network, APIPA addresses often indicate a DHCP server outage, a misconfigured DHCP relay (IP helper), or a VLAN mismatch that prevents DHCP discovery broadcasts from reaching the server.
KKey Concepts to Remember
APIPA addresses are in the 169.254.0.0/16 range.
APIPA automatically assigns an IP when DHCP fails.
APIPA allows local network communication only.
DHCP server unavailability triggers APIPA.
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
APIPA addresses are in the 169.254.0.0/16 range.
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 — APIPA addresses are in the 169.254.0.0/16 range..
What is the correct answer to this question?
The correct answer is: The DHCP server is unavailable — The IP address 169.254.1.5 is an Automatic Private IP Addressing (APIPA) address (169.254.0.0/16 range), which Windows assigns when a DHCP client fails to receive a lease from a DHCP server. Since the workstation cannot obtain a valid IP configuration, it cannot communicate with any network resources, confirming that the DHCP server is unavailable.
What should I do if I get this N10-009 question wrong?
Review aPIPA addresses are in the 169.254.0.0/16 range., then practise related N10-009 questions on the same topic to reinforce the concept.
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?
APIPA addresses are in the 169.254.0.0/16 range.
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