- A
Hub
Why wrong: A hub operates at Layer 1 (physical layer) and blindly repeats signals to all ports.
- B
Switch
A switch forwards frames based on MAC addresses, operating at the data link layer.
- C
Router
Why wrong: A router operates at Layer 3 (network layer) and forwards packets based on IP addresses.
- D
Firewall
Why wrong: A firewall can operate at multiple layers, but its primary function is security filtering, not MAC-based forwarding.
Question 400 of 520
Switch Layer 2 Function
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.
Which of the following network devices operates primarily at Layer 2 of the OSI model and uses MAC addresses to forward data?
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 primarily at Layer 2 (Data Link layer) of the OSI model, forwarding frames based on destination MAC addresses. It builds a MAC address table by learning source MAC addresses from incoming frames and uses this table to make forwarding decisions, 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
A hub operates at Layer 1 (physical layer) and blindly repeats signals to all ports.
When this WOULD be correct
A hub would be the correct answer if the question asked: 'Which device operates at Layer 1 and forwards data based on electrical signals?'
- ✓
Switch
Why this is correct
A switch forwards frames based on MAC addresses, operating at the data link layer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Router
Why it's wrong here
A router operates at Layer 3 (network layer) and forwards packets based on IP addresses.
When this WOULD be correct
A router would be the correct answer for a question like: 'Which network device operates at Layer 3 and uses IP addresses to determine the best path for data packets?'
- ✗
Firewall
Why it's wrong here
A firewall can operate at multiple layers, but its primary function is security filtering, not MAC-based forwarding.
When this WOULD be correct
A question asking 'Which network security device filters traffic based on IP addresses and port numbers?' would make firewall the correct answer, as it inspects packets at Layer 3 and above.
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
A switch forwards frames based on MAC addresses, operating at the data link layer.
✗HubWrong answer — click to see why▾
Why this is wrong here
A hub operates at Layer 1 (physical layer) and simply repeats electrical signals to all ports; it does not use MAC addresses to forward data.
★ When this WOULD be the correct answer
A hub would be the correct answer if the question asked: 'Which device operates at Layer 1 and forwards data based on electrical signals?'
Why candidates choose this
Candidates may confuse hubs with switches because both are used to connect multiple devices in a LAN, but hubs lack the intelligence to use MAC addresses.
✗RouterWrong answer — click to see why▾
Why this is wrong here
A router operates primarily at Layer 3 (Network layer) and uses IP addresses for forwarding decisions, not MAC addresses. It does not forward based on MAC addresses as a Layer 2 switch does.
★ When this WOULD be the correct answer
A router would be the correct answer for a question like: 'Which network device operates at Layer 3 and uses IP addresses to determine the best path for data packets?'
Why candidates choose this
Candidates may confuse the roles of switches and routers, thinking both forward data based on addresses, but they forget that routers use IP addresses (Layer 3) while switches use MAC addresses (Layer 2).
✗FirewallWrong answer — click to see why▾
Why this is wrong here
A firewall operates at Layer 3 (or higher) of the OSI model, using IP addresses and port numbers to filter traffic, not MAC addresses for forwarding decisions.
★ When this WOULD be the correct answer
A question asking 'Which network security device filters traffic based on IP addresses and port numbers?' would make firewall the correct answer, as it inspects packets at Layer 3 and above.
Why candidates choose this
Candidates may confuse firewalls with switches because both are common network devices, and some firewalls can perform basic Layer 2 functions, leading to the mistaken belief that they primarily use MAC addresses.
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 a switch (Layer 2, MAC-based forwarding) and a router (Layer 3, IP-based forwarding), and the trap here is that candidates may confuse a switch's ability to segment collision domains with routing functionality, or mistakenly think a switch uses IP addresses for forwarding decisions.
Detailed technical explanation
How to think about this question
Switches use the Spanning Tree Protocol (STP, IEEE 802.1D) to prevent loops in redundant topologies by blocking certain ports, while still learning MAC addresses. In a real-world scenario, a switch's MAC address table can overflow if flooded with many unique source MACs (e.g., from a MAC flooding attack), causing the switch to fall back to flooding frames like a hub, which can be exploited for packet sniffing.
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.
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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 primarily at Layer 2 (Data Link layer) of the OSI model, forwarding frames based on destination MAC addresses. It builds a MAC address table by learning source MAC addresses from incoming frames and uses this table to make forwarding decisions, 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
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 →
Same concept, more angles
1 more ways this is tested on N10-009
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A network technician is explaining the role of a network switch to a new employee. Which of the following best describes the primary function of a switch in a local area network?
easy- A.It forwards data based on IP addresses.
- ✓ B.It forwards data based on MAC addresses.
- C.It connects different networks and performs routing.
- D.It amplifies and repeats the signal to all ports.
Why B: A network switch operates at Layer 2 of the OSI model and uses MAC addresses to make forwarding decisions. When a frame arrives, the switch examines the destination MAC address, looks it up in its MAC address table, and forwards the frame only to the port associated with that address, reducing collision domains and improving network efficiency.
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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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