- A
Hub
Why wrong: Hubs operate at Layer 1 and simply repeat signals to all ports.
- B
Switch
Switches use MAC addresses to forward frames at Layer 2.
- C
Router
Why wrong: Routers operate at Layer 3 and use IP addresses to forward packets.
- D
Firewall
Why wrong: Firewalls typically inspect traffic at Layer 4 and above, though some have L2 capabilities.
Question 137 of 520
N10-009 Networking Concepts Practice Question
This N10-009 practice question tests your understanding of networking concepts. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 junior network technician asks which device operates at Layer 2 of the OSI model and uses MAC addresses to forward frames. Which device is the technician describing?
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
✓
Switch
A switch operates at Layer 2 (Data Link layer) of the OSI model and uses MAC addresses to make forwarding decisions. It builds a MAC address table by learning source MAC addresses from incoming frames and then forwards frames only to the specific port associated with the destination MAC address, reducing collision domains and improving network efficiency.
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.
- ✗
Hub
Why it's wrong here
Hubs operate at Layer 1 and simply repeat signals to all ports.
When this WOULD be correct
A question asking 'Which device operates at Layer 1 of the OSI model and regenerates signals?' would have Hub as the correct answer.
- ✓
Switch
Why this is correct
Switches use MAC addresses to forward frames at Layer 2.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Router
Why it's wrong here
Routers operate at Layer 3 and use IP addresses to forward packets.
When this WOULD be correct
A question asking 'Which device operates at Layer 3 of the OSI model and uses IP addresses to route packets between networks?' would make Router the correct answer.
- ✗
Firewall
Why it's wrong here
Firewalls typically inspect traffic at Layer 4 and above, though some have L2 capabilities.
When this WOULD be correct
A question asking 'Which device is used to filter traffic based on IP addresses and ports to protect a network from unauthorized access?' would have firewall as the correct answer.
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.
✓SwitchCorrect answer▾
Why this is correct
Switches use MAC addresses to forward frames at Layer 2.
✗HubWrong answer — click to see why▾
Why this is wrong here
Hubs operate at Layer 1 (Physical layer) and simply repeat electrical signals to all ports; they do not use MAC addresses to forward frames.
★ When this WOULD be the correct answer
A question asking 'Which device operates at Layer 1 of the OSI model and regenerates signals?' would have Hub as the correct answer.
Why candidates choose this
Candidates may confuse hubs with switches because both have multiple ports and are used in LANs, but hubs lack the intelligence to process MAC addresses.
✗RouterWrong answer — click to see why▾
Why this is wrong here
Routers operate at Layer 3 (Network layer) and use IP addresses to forward packets, not MAC addresses to forward frames.
★ When this WOULD be the correct answer
A question asking 'Which device operates at Layer 3 of the OSI model and uses IP addresses to route packets between networks?' would make Router the correct answer.
Why candidates choose this
Candidates may confuse the functions of switches and routers, especially if they recall that routers forward traffic but forget the layer distinction.
✗FirewallWrong answer — click to see why▾
Why this is wrong here
A firewall operates at Layers 3 and 4 (and sometimes higher) of the OSI model, using IP addresses and ports to filter traffic, not MAC addresses to forward frames.
★ When this WOULD be the correct answer
A question asking 'Which device is used to filter traffic based on IP addresses and ports to protect a network from unauthorized access?' would have firewall as the correct answer.
Why candidates choose this
Candidates may confuse firewalls with switches because both are network devices that filter traffic, but they operate at different layers and use different addressing.
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 N10-009 exam often tests the distinction between Layer 2 and Layer 3 devices by asking about forwarding decisions based on MAC vs. IP addresses, and the trap here is that candidates may confuse a switch with a router because both can connect multiple devices, but only the switch operates purely at Layer 2 using MAC addresses.
Detailed technical explanation
How to think about this question
Switches maintain a Content Addressable Memory (CAM) table that maps MAC addresses to specific ports; when a frame arrives with an unknown destination MAC, the switch floods the frame out all ports except the ingress port (unknown unicast flooding). In a real-world scenario, a switch can also implement Spanning Tree Protocol (STP) to prevent loops while still forwarding at Layer 2, a behavior not possible with hubs or routers.
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
Learn the concepts, then practise the questions
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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: Switch — A switch operates at Layer 2 (Data Link layer) of the OSI model and uses MAC addresses to make forwarding decisions. It builds a MAC address table by learning source MAC addresses from incoming frames and then forwards frames only to the specific port associated with the destination MAC address, reducing collision domains and improving network efficiency.
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
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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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