Quick Answer
The answer is a switch. A switch operates at Layer 2 of the OSI model, the Data Link layer, and uses MAC addresses to forward frames by building a MAC address table that maps each source MAC address to the specific port where it was learned; when a frame arrives, the switch checks the destination MAC address and forwards it only out the corresponding port, which reduces collision domains and boosts network efficiency. On the CompTIA Network+ N10-009 exam, this concept tests your understanding of how switches differ from hubs (which flood all ports) and routers (which operate at Layer 3 using IP addresses)—a common trap is confusing a switch’s MAC-based forwarding with a router’s IP-based routing. To remember, think: “Switch sorts by MAC, router routes by IP.”
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?
Hub
Why wrong: Hubs operate at Layer 1 and simply repeat signals to all ports.
Switch
Switches use MAC addresses to forward frames at Layer 2.
Router
Why wrong: Routers operate at Layer 3 and use IP addresses to forward packets.
Firewall
Why wrong: Firewalls typically inspect traffic at Layer 4 and above, though some have L2 capabilities.
Answer choices
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
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.
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.
Firewall
Why it's wrong here
Firewalls typically inspect traffic at Layer 4 and above, though some have L2 capabilities.
Common exam traps
Cisco 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
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.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Networking Concepts — study guide chapter
Learn the concepts, then practise the questions
Networking Concepts practice questions
Targeted practice on this topic area only
All N10-009 questions
520 questions across all exam domains
CompTIA Network+ N10-009 study guide
Full concept coverage aligned to exam objectives
N10-009 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Practise N10-009 questions linked to Networking Concepts.
Practise N10-009 questions linked to Network Implementation.
Practise N10-009 questions linked to Network Operations.
Practise N10-009 questions linked to Network Security.
Practise N10-009 questions linked to Network Troubleshooting.
Practise N10-009 questions linked to Network+ network fundamentals.
Practice this exam
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Networking Concepts — This question tests Networking Concepts — Read the scenario before looking for a memorised answer..
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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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 →
Keep practising
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.