N10-009 Networking Concepts Practice Question
Which of the following network devices operates at Layer 1 of the OSI model and forwards all incoming electrical signals to all of its ports?
⚠ Common exam trap
The N10-009 exam often tests the distinction between a hub and a switch, where candidates mistakenly think a switch forwards all incoming traffic to all ports (like a hub) because they confuse broadcast traffic with general forwarding behavior.
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
✓
Hub
A hub operates at Layer 1 (Physical layer) of the OSI model and is a multiport repeater. It regenerates and forwards every incoming electrical signal out of all ports except the incoming port, regardless of the intended destination, because it has no intelligence to process MAC addresses or frames.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Router
Why it's wrong here
A router operates at Layer 3, the Network layer, and is responsible for forwarding data packets between different logical networks or subnets. It makes intelligent forwarding decisions based on the destination IP addresses contained within the packet headers, utilizing routing tables to determine the optimal path. Unlike Layer 1 devices, routers actively manage network traffic flow and segment broadcast domains, enabling communication across disparate networks.
When this WOULD be correct
A router would be the correct answer for a question asking: 'Which network device connects different networks and makes forwarding decisions based on logical addressing?'
- ✗
Switch
Why it's wrong here
A network switch operates at Layer 2, the Data Link layer, and intelligently forwards data frames based on destination MAC addresses. By learning the MAC addresses of connected devices and storing them in its MAC address table, a switch can direct frames only to the intended recipient port, significantly reducing unnecessary traffic. This creates dedicated collision domains for each port, enhancing network efficiency and performance compared to a hub.
When this WOULD be correct
A switch would be correct for a question asking: 'Which device uses MAC addresses to forward frames only to the intended recipient port?' or 'Which device operates at Layer 2 and reduces collision domains?'
- ✓
Hub
Why this is correct
A hub is a fundamental Layer 1 device operating at the Physical layer of the OSI model. It functions as a multi-port repeater, regenerating incoming electrical signals and broadcasting them to all connected ports without any form of intelligence or filtering. This creates a single, large collision domain, meaning all devices connected to the hub share the same network segment and contend for bandwidth.
- ✗
Bridge
Why it's wrong here
A bridge functions at Layer 2, the Data Link layer, to connect two or more network segments and filter traffic based on MAC addresses. It learns the MAC addresses of devices on each segment and forwards frames only when the destination MAC address is located on a different segment. Historically, bridges were used to segment larger collision domains into smaller ones, providing an early form of network segmentation before the widespread adoption of multi-port switches.
When this WOULD be correct
A bridge would be the correct answer for a question asking: 'Which network device connects two separate LAN segments and forwards frames based on MAC addresses?'
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.
✓HubCorrect answer▾
Why this is correct
A hub is a fundamental Layer 1 device operating at the Physical layer of the OSI model. It functions as a multi-port repeater, regenerating incoming electrical signals and broadcasting them to all connected ports without any form of intelligence or filtering. This creates a single, large collision domain, meaning all devices connected to the hub share the same network segment and contend for bandwidth.
✗RouterWrong answer — click to see why▾
Why this is wrong here
A router operates at Layer 3 (Network layer) and makes forwarding decisions based on IP addresses, not by blindly forwarding electrical signals to all ports.
★ When this WOULD be the correct answer
A router would be the correct answer for a question asking: 'Which network device connects different networks and makes forwarding decisions based on logical addressing?'
Why candidates choose this
Candidates may confuse routers with hubs because both can connect multiple devices, but they forget that routers operate at higher layers and do not forward all signals indiscriminately.
✗SwitchWrong answer — click to see why▾
Why this is wrong here
A switch operates at Layer 2 (Data Link) and uses MAC addresses to selectively forward frames only to the destination port, not to all ports like a hub.
★ When this WOULD be the correct answer
A switch would be correct for a question asking: 'Which device uses MAC addresses to forward frames only to the intended recipient port?' or 'Which device operates at Layer 2 and reduces collision domains?'
Why candidates choose this
Candidates may confuse hubs and switches because both are used to connect multiple devices in a LAN, and they might not recall that hubs are Layer 1 repeaters while switches are Layer 2.
✗BridgeWrong answer — click to see why▾
Why this is wrong here
A bridge operates at Layer 2, not Layer 1, and it forwards frames based on MAC addresses, not all electrical signals to all ports.
★ When this WOULD be the correct answer
A bridge would be the correct answer for a question asking: 'Which network device connects two separate LAN segments and forwards frames based on MAC addresses?'
Why candidates choose this
Candidates may confuse bridges with hubs because both are legacy devices that connect network segments, but bridges make forwarding decisions at Layer 2.
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
Open Systems Interconnection
The Open Systems Interconnection (OSI) model is a conceptual framework used to understand how data travels from one computer to another across a network.
About these practice questions
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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.