N10-009 Networking Concepts Practice Question
Which of the following network devices operates primarily at Layer 2 of the OSI model and uses MAC addresses to forward data?
⚠ Common exam trap
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.
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.
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 exclusively at Layer 1 (Physical Layer) of the OSI model. It functions as a multi-port repeater, receiving an electrical signal on one port and blindly regenerating and broadcasting it to all other connected ports without any intelligence or frame inspection. This creates a single large collision domain, leading to inefficient network utilization and frequent collisions in half-duplex environments.
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 network switch operates primarily at Layer 2 (Data Link Layer) of the OSI model. It intelligently forwards Ethernet frames to specific destination ports based on the MAC addresses learned and stored in its Content Addressable Memory (CAM) table. This targeted forwarding significantly reduces network congestion by creating micro-segments and eliminating collision domains, unlike a hub.
- ✗
Router
Why it's wrong here
A router operates primarily at Layer 3 (Network Layer) of the OSI model, making forwarding decisions based on logical IP addresses. Its main function is to connect different IP networks or subnets, using routing tables to determine the optimal path for forwarding IP packets between them. Routers also break up broadcast domains, unlike switches which break up collision domains.
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 is a security device designed to monitor and control incoming and outgoing network traffic based on predefined security rules. While some advanced firewalls can inspect traffic at Layer 2, their primary operational focus and filtering capabilities extend across Layer 3 (Network Layer) and often up to Layer 7 (Application Layer) for stateful packet inspection and application-level filtering. Its core function is security, not efficient local frame 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 network switch operates primarily at Layer 2 (Data Link Layer) of the OSI model. It intelligently forwards Ethernet frames to specific destination ports based on the MAC addresses learned and stored in its Content Addressable Memory (CAM) table. This targeted forwarding significantly reduces network congestion by creating micro-segments and eliminating collision domains, unlike a hub.
✗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?”
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 |
Go deeper
Related to this question
Learn chapter
Network Virtualization and VXLAN
Key term
OSI model
The OSI model is a conceptual framework that standardizes the functions of a telecommunication or computing system into seven distinct layers, from physical hardware to application software.
Key term
MAC address table
A MAC address table is a data structure stored in a network switch that maps each of its ports to the MAC addresses of connected devices, enabling the switch to forward frames only to the correct destination.
About these practice questions
Courseiva writes every N10-009 question from scratch — 464 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
Same concept, more angles
1 more way 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.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.