The answer is a router, because it operates at Layer 3 of the OSI model and forwards traffic based on IP addresses, making it the correct device for connecting two distinct networks. Unlike switches or hubs, which work at Layers 2 and 1, a router uses routing tables and protocols like OSPF or BGP to examine the destination IP address and determine the optimal path for packets between different subnets. On the CompTIA Network+ N10-009 exam, this concept tests your understanding of OSI layer functions and device roles—a common trap is confusing a Layer 3 switch with a router, but remember that while both can route, a dedicated router is the standard answer for connecting separate networks. For a quick memory tip, think “Router reads the IP” to recall that Layer 3 forwarding decisions are based on logical addresses, not MAC addresses.
N10-009 Networking Concepts Practice Question
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 technician needs to connect two different networks and forward traffic based on IP addresses. Which of the following devices operates at Layer 3 of the OSI model and should be used?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Router
A router operates at Layer 3 (Network layer) of the OSI model and makes forwarding decisions based on IP addresses. It uses routing tables and protocols such as OSPF or BGP to determine the best path for packets between different networks. This makes it the correct device for connecting two distinct networks and forwarding traffic by IP address.
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
Hubs operate at Layer 1 and simply repeat electrical signals; they do not make forwarding decisions based on IP addresses.
✗
Switch
Why it's wrong here
Switches operate at Layer 2 and forward frames based on MAC addresses, not IP addresses.
✓
Router
Why this is correct
Routers are Layer 3 devices that forward packets based on IP addresses, enabling communication between different networks.
Related concept
Read the scenario before looking for a memorised answer.
✗
Bridge
Why it's wrong here
Bridges operate at Layer 2 and segment a network based on MAC addresses; they do not route based on IP addresses.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CompTIA often tests the misconception that a 'multilayer switch' can replace a router for all Layer 3 functions, but the question specifically asks for a device that operates at Layer 3 and forwards based on IP addresses, and a standard switch (even a Layer 3 switch) is still primarily a switch; the correct answer is always the router when the context is connecting different networks.
Detailed technical explanation
How to think about this question
Routers maintain a routing table that contains destination network prefixes, next-hop addresses, and metrics; when a packet arrives, the router performs a longest-prefix match on the destination IP address to select the correct outgoing interface. In real-world scenarios, routers also perform Network Address Translation (NAT) and implement access control lists (ACLs) to filter traffic based on IP addresses. The distinction between routing (Layer 3) and switching (Layer 2) is fundamental to network design, as routers enable communication between different subnets or VLANs.
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 network engineer at a university connects two campus buildings via a fibre link. Both routers run OSPF, but no adjacency forms — even though both routers can ping each other. The engineer finds one router is in area 0 and the other in area 1. OSPF adjacency requires matching area numbers, hello/dead timers, and network type. IP reachability alone is not enough.
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: Router — A router operates at Layer 3 (Network layer) of the OSI model and makes forwarding decisions based on IP addresses. It uses routing tables and protocols such as OSPF or BGP to determine the best path for packets between different networks. This makes it the correct device for connecting two distinct networks and forwarding traffic by IP address.
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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