The correct answer is the Network layer, Layer 3 of the OSI model. This layer is responsible for logical addressing, such as IPv4 and IPv6 addresses, and for routing packets between different networks by determining the best path for data delivery. On the CompTIA Network+ N10-009 exam, this concept is frequently tested to ensure you understand that routers operate at Layer 3, using routing tables and protocols like OSPF and BGP, while switches typically work at Layer 2 with MAC addresses. A common trap is confusing logical addressing with physical addressing—remember that IP addresses are logical and routable, while MAC addresses are physical and confined to a local network. To lock it in, use the mnemonic "Please Do Not Throw Sausage Pizza Away" where the third word, "Not," stands for Network layer, the home of logical addressing and routing.
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.
At which layer of the OSI model does logical addressing (e.g., IP addresses) and routing occur?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Network layer
The Network layer (Layer 3) of the OSI model is responsible for logical addressing, such as IPv4 and IPv6 addresses, and for routing packets between different networks. Routers operate at this layer, using routing tables and protocols like OSPF, BGP, or static routes to determine the best path for data. This layer provides end-to-end delivery and handles packet fragmentation and reassembly when necessary.
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.
✗
Data Link layer
Why it's wrong here
The Data Link layer (Layer 2) handles physical addressing (MAC addresses) and switching within a local network.
✓
Network layer
Why this is correct
The Network layer (Layer 3) uses IP addresses for logical addressing and routing decisions.
Related concept
Read the scenario before looking for a memorised answer.
✗
Transport layer
Why it's wrong here
The Transport layer (Layer 4) provides reliable or unreliable delivery and segmentation, not routing.
✗
Physical layer
Why it's wrong here
The Physical layer (Layer 1) defines hardware specifications like cables and signals.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse the Network layer's logical addressing with the Data Link layer's MAC addressing, especially when they see 'addressing' in the question and default to Layer 2 without considering the 'routing' keyword that clearly points to Layer 3.
Detailed technical explanation
How to think about this question
Logical addressing at the Network layer uses hierarchical IP addresses (e.g., 192.168.1.1/24) that include a network portion and a host portion, enabling routers to aggregate routes and scale the internet. Routing protocols like OSPF use link-state advertisements (LSAs) to build a complete topology map, while BGP uses path-vector attributes to make policy-based routing decisions across autonomous systems. A subtle behavior is that routers perform a longest-prefix match on the destination IP address against the routing table to forward packets, which can lead to unexpected behavior if overlapping routes exist.
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: Network layer — The Network layer (Layer 3) of the OSI model is responsible for logical addressing, such as IPv4 and IPv6 addresses, and for routing packets between different networks. Routers operate at this layer, using routing tables and protocols like OSPF, BGP, or static routes to determine the best path for data. This layer provides end-to-end delivery and handles packet fragmentation and reassembly when necessary.
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 →
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. Which layer of the OSI model is responsible for logical addressing and routing of packets between networks?
easy
A.Data Link layer
✓ B.Network layer
C.Transport layer
D.Application layer
Why B: The Network layer (Layer 3) is responsible for logical addressing (e.g., IPv4/IPv6 addresses) and routing packets between different networks by determining the best path using routing protocols such as OSPF, BGP, or static routes. Unlike the Data Link layer, which handles physical addressing (MAC) within a single network segment, the Network layer enables end-to-end delivery across multiple hops.
Last reviewed: Jun 11, 2026
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.