- A
MAC address
A MAC address is a 48-bit hardware address assigned to each network interface card (NIC) for local network communications.
- B
IP address
Why wrong: An IP address identifies a device on a network but can change (DHCP) and does not uniquely identify the hardware interface.
- C
Subnet mask
Why wrong: The subnet mask is used for network division, not for identifying a specific hardware interface.
- D
Default gateway
Why wrong: The default gateway is the IP address of a router used to reach remote networks, not a hardware identifier.
Question 168 of 520
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.
Which of the following uniquely identifies a hardware network interface on a device?
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
✓
MAC address
A MAC (Media Access Control) address is a hardware-embedded, globally unique identifier assigned to a network interface controller (NIC) by the manufacturer. It operates at Layer 2 (Data Link Layer) of the OSI model and is used for local network communication, ensuring that no two devices on the same broadcast domain have the same MAC 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.
- ✓
MAC address
Why this is correct
A MAC address is a 48-bit hardware address assigned to each network interface card (NIC) for local network communications.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
IP address
Why it's wrong here
An IP address identifies a device on a network but can change (DHCP) and does not uniquely identify the hardware interface.
When this WOULD be correct
When a question asks 'Which of the following identifies a device on a network for routing purposes?' or 'Which address is used for communication between networks?', IP address would be correct.
- ✗
Subnet mask
Why it's wrong here
The subnet mask is used for network division, not for identifying a specific hardware interface.
When this WOULD be correct
In a question asking 'Which value determines the network portion of an IP address?', the subnet mask would be the correct answer.
- ✗
Default gateway
Why it's wrong here
The default gateway is the IP address of a router used to reach remote networks, not a hardware identifier.
When this WOULD be correct
In a question asking 'Which IP address should be configured as the next-hop for traffic destined to the internet?', the default gateway would be the correct answer.
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.
✓MAC addressCorrect answer▾
Why this is correct
A MAC address is a 48-bit hardware address assigned to each network interface card (NIC) for local network communications.
✗IP addressWrong answer — click to see why▾
Why this is wrong here
An IP address identifies a device on a network layer, not the hardware interface itself, and can change dynamically or be reassigned.
★ When this WOULD be the correct answer
When a question asks 'Which of the following identifies a device on a network for routing purposes?' or 'Which address is used for communication between networks?', IP address would be correct.
Why candidates choose this
Candidates often confuse network-layer identification (IP) with hardware-layer identification (MAC), especially when thinking about 'identifying a device' on a network.
✗Subnet maskWrong answer — click to see why▾
Why this is wrong here
A subnet mask defines the network and host portions of an IP address, but it does not uniquely identify a hardware network interface; it is a logical parameter used for routing.
★ When this WOULD be the correct answer
In a question asking 'Which value determines the network portion of an IP address?', the subnet mask would be the correct answer.
Why candidates choose this
Candidates may confuse subnet masks with MAC addresses because both are associated with network configuration, or they might think the subnet mask is tied to the interface in some unique way.
✗Default gatewayWrong answer — click to see why▾
Why this is wrong here
A default gateway is a router's IP address used for traffic outside the local subnet, not a unique identifier for a hardware network interface.
★ When this WOULD be the correct answer
In a question asking 'Which IP address should be configured as the next-hop for traffic destined to the internet?', the default gateway would be the correct answer.
Why candidates choose this
Candidates may confuse the default gateway as a network identifier because it is a critical network setting often associated with a specific interface, but it does not uniquely identify the interface itself.
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 the MAC address with the IP address, thinking the IP address is the hardware identifier, but CompTIA tests that the MAC address is the only Layer 2 permanent identifier, while IP addresses are logical and can be reassigned via DHCP or static configuration.
Detailed technical explanation
How to think about this question
Under the hood, a MAC address is a 48-bit (6-byte) value typically expressed in hexadecimal, with the first 24 bits (OUI) assigned by the IEEE to the manufacturer and the remaining 24 bits uniquely assigned by the vendor. In real-world scenarios, MAC addresses can be spoofed or randomized (e.g., in modern iOS/Android privacy features), but the original burned-in address (BIA) remains the true hardware identifier stored in the NIC's firmware.
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 segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.
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 |
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
- →
Networking Concepts — study guide chapter
Learn the concepts, then practise the questions
- →
Networking Concepts practice questions
Targeted practice on this topic area only
- →
All N10-009 questions
520 questions across all exam domains
- →
CompTIA Network+ N10-009 study guide
Full concept coverage aligned to exam objectives
- →
N10-009 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Related N10-009 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Networking Concepts practice questions
Practise N10-009 questions linked to Networking Concepts.
Network Implementation practice questions
Practise N10-009 questions linked to Network Implementation.
Network Operations practice questions
Practise N10-009 questions linked to Network Operations.
Network Security practice questions
Practise N10-009 questions linked to Network Security.
Network Troubleshooting practice questions
Practise N10-009 questions linked to Network Troubleshooting.
Network+ network fundamentals practice questions
Practise N10-009 questions linked to Network+ network fundamentals.
Practice this exam
Start a free N10-009 practice session
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
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: MAC address — A MAC (Media Access Control) address is a hardware-embedded, globally unique identifier assigned to a network interface controller (NIC) by the manufacturer. It operates at Layer 2 (Data Link Layer) of the OSI model and is used for local network communication, ensuring that no two devices on the same broadcast domain have the same MAC 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.
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 →
Keep practising
More N10-009 practice questions
- Which of the following network devices operates primarily at Layer 2 of the OSI model and uses MAC addresses to forward…
- Which of the following is a characteristic of UDP when compared to TCP?
- Which of the following IPv6 addresses is a valid link-local address?
- Which of the following security mechanisms requires a user to authenticate before gaining access to the wired network at…
- Which of the following network protocols operates at the Transport layer of the OSI model and provides connection-orient…
- Which of the following is a characteristic of a connectionless protocol at the transport layer?
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.
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.