N10-009 Network Troubleshooting Practice Question
A network administrator notices that a workstation cannot connect to any network resources. The workstation's IP configuration shows an IP address of 169.254.10.5 with a subnet mask of 255.255.0.0 and no default gateway. The administrator verifies that the switch port is active and the cable is connected. Which of the following is the most likely cause?
⚠ Common exam trap
The trap here is focusing on the missing default gateway as the problem, when the APIPA address is the key clue pointing to a DHCP failure.
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 responding.
The correct answer is that the DHCP server is unreachable or not responding. The APIPA address (169.254.x.x) is a clear indicator that the workstation could not obtain a DHCP lease. The other options are incorrect because they do not explain the APIPA address; a static IP misconfiguration would show a different address, DNS issues would not affect DHCP, and a default gateway misconfiguration is a consequence of DHCP failure, not the cause.
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 not configured correctly.
Why it's wrong here
DNS issues would not prevent the workstation from obtaining an IP address via DHCP. The workstation has an APIPA address, indicating a DHCP failure, not a DNS problem. DNS resolution would only affect name resolution after IP connectivity is established.
- ✗
The default gateway is misconfigured on the workstation.
Why it's wrong here
A missing or incorrect default gateway would not cause the workstation to self-assign an APIPA address. The APIPA address specifically indicates that DHCP failed. The default gateway is typically provided by DHCP, so its absence is a symptom, not the root cause.
- ✗
The workstation is configured with a static IP address in the wrong subnet.
Why it's wrong here
A static IP misconfiguration would typically result in an IP address from the configured subnet, not an APIPA address. The presence of a 169.254.x.x address indicates the workstation did not receive a DHCP lease, so static configuration is not the issue.
- ✓
The DHCP server is unreachable or not responding.
Why this is correct
The 169.254.x.x address is an Automatic Private IP Addressing (APIPA) address, which Windows assigns when a DHCP server cannot be reached. Since the switch port is active, the most likely cause is that the DHCP server is down, out of addresses, or the DHCP relay is not configured.
Visual reference
Go deeper
Related to this question
Learn chapter
Default Gateway Configuration Issues
Key term
DHCP server
A DHCP server is a network device or service that automatically assigns IP addresses and other network configuration parameters to devices on a network, eliminating the need for manual configuration.
Key term
Automatic Private Internet Protocol Addressing
A fallback method used by a device to automatically assign itself an IP address when it cannot obtain one from a DHCP server.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official CompTIA exam blueprint
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.