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 at Layer 1 of the OSI model and forwards all incoming electrical signals to all of its ports?
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.
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.
✗
Router
Why it's wrong here
A router operates at Layer 3 (Network layer) and makes forwarding decisions based on IP addresses, not Layer 1.
✗
Switch
Why it's wrong here
A switch operates at Layer 2 (Data Link layer) and forwards frames based on MAC addresses, not Layer 1.
✓
Hub
Why this is correct
A hub is a Layer 1 device that repeats all incoming signals to all ports without any intelligence or filtering.
Related concept
Read the scenario before looking for a memorised answer.
✗
Bridge
Why it's wrong here
A bridge operates at Layer 2 and forwards frames based on MAC addresses, not Layer 1.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco 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.
Detailed technical explanation
How to think about this question
Hubs use a shared bus topology internally, meaning all ports are electrically connected; when a signal arrives, it is electrically repeated and broadcast to all other ports, causing collisions in half-duplex mode. This behavior is defined by IEEE 802.3 for repeater hubs, and in modern networks, hubs are largely obsolete due to collision domain and bandwidth inefficiency compared to switches.
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 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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this N10-009 question in full detail.
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: 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.
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.
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Question Discussion
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