- A
Transport layer
Why wrong: The Transport layer is responsible for end-to-end communication and segmentation, not physical cabling.
- B
Data Link layer
Why wrong: The Data Link layer handles framing and MAC addressing, but not the physical medium itself.
- C
Physical layer
The Physical layer defines the electrical, mechanical, and procedural interface to the transmission medium, making it the correct layer for cabling issues.
- D
Network layer
Why wrong: The Network layer handles logical addressing and routing, not physical connections.
Question 519 of 520
N10-009 Networking Concepts Practice Question
This N10-009 practice question tests your understanding of networking concepts. 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 network administrator is troubleshooting a connectivity issue and suspects the problem is related to the physical cabling. At which layer of the OSI model should the administrator begin their investigation?
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
✓
Physical layer
The Physical layer (Layer 1) is the correct starting point because the administrator suspects the problem is related to physical cabling. The Physical layer defines the electrical, mechanical, and procedural specifications for transmitting raw bits over a physical medium, such as copper or fiber optic cables. Troubleshooting at this layer involves checking for cable faults, signal degradation, or improper termination before moving up the OSI stack.
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.
- ✗
Transport layer
Why it's wrong here
The Transport layer is responsible for end-to-end communication and segmentation, not physical cabling.
- ✗
Data Link layer
Why it's wrong here
The Data Link layer handles framing and MAC addressing, but not the physical medium itself.
When this WOULD be correct
A question asking where to investigate issues with MAC address conflicts, frame errors, or switch port configuration (e.g., duplex mismatch) would make the Data Link layer the correct starting point.
- ✓
Physical layer
Why this is correct
The Physical layer defines the electrical, mechanical, and procedural interface to the transmission medium, making it the correct layer for cabling issues.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Network layer
Why it's wrong here
The Network layer handles logical addressing and routing, not physical connections.
When this WOULD be correct
This option would be correct if the question asked about troubleshooting a routing issue, such as incorrect IP configuration or a routing table problem, where the investigation should start at the Network layer.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The N10-009 exam frequently reuses these exact scenarios with slightly different constraints.
✓Physical layerCorrect answer▾
Why this is correct
The Physical layer defines the electrical, mechanical, and procedural interface to the transmission medium, making it the correct layer for cabling issues.
✗Transport layerWrong answer — click to see why▾
Why this is wrong here
The question specifies a physical cabling issue, which is a Layer 1 (Physical layer) problem. The Transport layer (Layer 4) deals with end-to-end communication and data segmentation, not physical media.
★ When this WOULD be the correct answer
A question about troubleshooting a connectivity issue where the problem is suspected to be related to port numbers, session multiplexing, or reliable data delivery (e.g., TCP vs UDP issues) would make the Transport layer the correct starting point.
Why candidates choose this
Candidates may confuse the OSI layers and think that all connectivity issues start at higher layers, or they may recall that the Transport layer is involved in end-to-end connectivity, but they overlook the specific mention of physical cabling.
✗Data Link layerWrong answer — click to see why▾
Why this is wrong here
The Data Link layer (Layer 2) handles framing, MAC addressing, and error detection, but not the physical cabling itself. The question specifically states the issue is related to physical cabling, which is Layer 1.
★ When this WOULD be the correct answer
A question asking where to investigate issues with MAC address conflicts, frame errors, or switch port configuration (e.g., duplex mismatch) would make the Data Link layer the correct starting point.
Why candidates choose this
Candidates may confuse the Data Link layer with physical cabling because it deals with network interfaces and media access control, or they might think troubleshooting always starts at Layer 2.
✗Network layerWrong answer — click to see why▾
Why this is wrong here
The Network layer (Layer 3) handles logical addressing and routing, not physical cabling issues. The administrator suspects a physical cabling problem, which is a Layer 1 concern.
★ When this WOULD be the correct answer
This option would be correct if the question asked about troubleshooting a routing issue, such as incorrect IP configuration or a routing table problem, where the investigation should start at the Network layer.
Why candidates choose this
Candidates may confuse the Network layer with physical connectivity because they associate 'network' with all networking hardware, or they may think IP addressing is involved in cable troubleshooting.
Analysis generated from the official N10-009blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often jump to the Data Link layer (Layer 2) because they associate 'connectivity issues' with MAC addresses or switching, forgetting that physical cabling faults must be ruled out first at Layer 1.
Detailed technical explanation
How to think about this question
At the Physical layer, issues like excessive attenuation, crosstalk, or impedance mismatches can cause bit errors that manifest as link flaps or CRC errors at Layer 2. Tools like a time-domain reflectometer (TDR) or cable tester are used to identify breaks, shorts, or length violations in copper cabling. In real-world scenarios, a miswired T568A/T568B termination can cause a link to fail at 1 Gbps but work at 100 Mbps, a subtle behavior that requires Layer 1 inspection.
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.
Quick reference
OSI Model Reference
| Layer | Name | PDU | Key Protocols / Devices |
|---|---|---|---|
| 7 | Application | Data | HTTP, HTTPS, DNS, SMTP, FTP, SSH |
| 6 | Presentation | Data | TLS / SSL, JPEG, ASCII encoding |
| 5 | Session | Data | NetBIOS, RPC, SIP |
| 4 | Transport | Segment / Datagram | TCP, UDP |
| 3 | Network | Packet | IP, ICMP, OSPF — Routers |
| 2 | Data Link | Frame | Ethernet, Wi-Fi, PPP — Switches, Bridges |
| 1 | Physical | Bits | Cables, NICs, Hubs, Repeaters |
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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Networking Concepts — study guide chapter
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FAQ
Questions learners often ask
What does this N10-009 question test?
Networking Concepts — This question tests Networking Concepts — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Physical layer — The Physical layer (Layer 1) is the correct starting point because the administrator suspects the problem is related to physical cabling. The Physical layer defines the electrical, mechanical, and procedural specifications for transmitting raw bits over a physical medium, such as copper or fiber optic cables. Troubleshooting at this layer involves checking for cable faults, signal degradation, or improper termination before moving up the OSI stack.
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 →
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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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