- A
Switch
Why wrong: A switch forwards frames based on MAC addresses at Layer 2, not IP addresses.
- B
Bridge
Why wrong: A bridge also operates at Layer 2, forwarding based on MAC addresses.
- C
Router
A router routes packets based on Layer 3 IP addresses and maintains a routing table.
- D
Hub
Why wrong: A hub is a Layer 1 device that regenerates signals without any forwarding intelligence.
Question 509 of 520
Router Layer 3 Operation
This N10-009 practice question tests your understanding of networking concepts. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 devices operates at Layer 3 of the OSI model and makes forwarding decisions based on destination IP addresses?
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
✓
Router
A router operates at Layer 3 (Network layer) of the OSI model and uses the destination IP address in the packet header to make forwarding decisions. It maintains a routing table (e.g., via OSPF, EIGRP, or static routes) to determine the next-hop interface for each packet, enabling communication between different subnets or VLANs.
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.
- ✗
Switch
Why it's wrong here
A switch forwards frames based on MAC addresses at Layer 2, not IP addresses.
When this WOULD be correct
A switch would be the correct answer for a question asking which device operates at Layer 2 and forwards frames based on MAC addresses, or which device is used to connect multiple devices within a single LAN.
- ✗
Bridge
Why it's wrong here
A bridge also operates at Layer 2, forwarding based on MAC addresses.
When this WOULD be correct
A bridge would be the correct answer for a question asking which device connects two network segments and forwards frames based on MAC addresses, or which Layer 2 device reduces collision domains.
- ✓
Router
Why this is correct
A router routes packets based on Layer 3 IP addresses and maintains a routing table.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Hub
Why it's wrong here
A hub is a Layer 1 device that regenerates signals without any forwarding intelligence.
When this WOULD be correct
A hub would be the correct answer for a question asking which device operates at Layer 1 and forwards data based on electrical signals, not addressing.
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.
✓RouterCorrect answer▾
Why this is correct
A router routes packets based on Layer 3 IP addresses and maintains a routing table.
✗SwitchWrong answer — click to see why▾
Why this is wrong here
A switch operates at Layer 2 of the OSI model and makes forwarding decisions based on MAC addresses, not destination IP addresses.
★ When this WOULD be the correct answer
A switch would be the correct answer for a question asking which device operates at Layer 2 and forwards frames based on MAC addresses, or which device is used to connect multiple devices within a single LAN.
Why candidates choose this
Candidates may confuse switches with routers because both are used for network connectivity, but they operate at different layers and use different addressing for forwarding decisions.
✗BridgeWrong answer — click to see why▾
Why this is wrong here
A bridge operates at Layer 2 of the OSI model and makes forwarding decisions based on MAC addresses, not IP addresses.
★ When this WOULD be the correct answer
A bridge would be the correct answer for a question asking which device connects two network segments and forwards frames based on MAC addresses, or which Layer 2 device reduces collision domains.
Why candidates choose this
Candidates may confuse bridges with routers because both connect networks and forward traffic, but they operate at different OSI layers.
✗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, making no forwarding decisions based on IP addresses.
★ When this WOULD be the correct answer
A hub would be the correct answer for a question asking which device operates at Layer 1 and forwards data based on electrical signals, not addressing.
Why candidates choose this
Candidates may confuse hubs with switches or routers because all are network devices, but they lack understanding of OSI layers and the specific functions of each device.
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?”
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse a Layer 3 switch with a router, but the question specifies a device that makes forwarding decisions based on destination IP addresses, which is the defining function of a router, not a switch (even a multilayer switch still uses MAC addresses for most forwarding unless explicitly configured for routing).
Detailed technical explanation
How to think about this question
Routers use longest-prefix matching in their routing table to select the most specific route for a destination IP, and they decrement the Time-to-Live (TTL) field in the IP header to prevent loops. In real-world scenarios, a router can also perform Network Address Translation (NAT) to map private IPs to a public IP, or act as a firewall using access control lists (ACLs) that filter based on Layer 3 information.
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.
Visual reference
Quick reference
Routing Protocol Comparison
| Protocol | Metric | Max Hops | Algorithm | Type |
|---|---|---|---|---|
| RIP v2 | Hop count | 15 | Bellman-Ford | Distance vector |
| OSPF | Cost (bandwidth) | Unlimited | Dijkstra (SPF) | Link state |
| EIGRP | Composite metric | Unlimited | DUAL | Hybrid |
| IS-IS | Cost | Unlimited | Dijkstra | Link state |
| BGP | Policy / attributes | Unlimited | Path vector | Path vector |
RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this N10-009 question test?
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 uses the destination IP address in the packet header to make forwarding decisions. It maintains a routing table (e.g., via OSPF, EIGRP, or static routes) to determine the next-hop interface for each packet, enabling communication between different subnets or VLANs.
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.
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 →
Same concept, more angles
1 more ways 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. At which OSI layer does a router primarily operate to make forwarding decisions based on IP addresses?
easy- A.Layer 1 (Physical)
- B.Layer 2 (Data Link)
- ✓ C.Layer 3 (Network)
- D.Layer 4 (Transport)
Why C: A router primarily operates at Layer 3 (Network) of the OSI model because it uses logical IP addresses (e.g., IPv4 or IPv6) to make forwarding decisions. The router examines the destination IP address in the packet header, performs a longest-prefix match against its routing table, and determines the next-hop interface. This layer is responsible for end-to-end delivery and path selection across multiple networks.
Keep practising
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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.
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