- A
Data Link layer (Layer 2)
MAC addresses are used at Layer 2 for local network communication.
- B
Transport layer (Layer 4)
Why wrong: Layer 4 deals with TCP/UDP segments and ports.
- C
Physical layer (Layer 1)
Why wrong: Layer 1 deals with bits, cables, and hubs, not MAC addresses.
- D
Network layer (Layer 3)
Why wrong: Layer 3 uses IP addresses, not MAC addresses.
Question 825 of 1,000
200-901 Network Fundamentals Practice Question
This 200-901 practice question tests your understanding of network fundamentals. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
An engineer is troubleshooting a network issue and needs to verify the MAC address of the next-hop router on a directly connected segment. Which layer of the OSI model does the engineer need to examine to find this information?
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
✓
Data Link layer (Layer 2)
The MAC address of the next-hop router is found in the Data Link layer (Layer 2) header of a frame. When a device sends an IP packet to a next-hop router on the same segment, it encapsulates the packet in a frame with the destination MAC address of that router's interface. To verify this address, you examine Layer 2 information, such as by using the `show arp` command on Cisco devices to view the MAC-to-IP mapping.
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 (Layer 2)
Why this is correct
MAC addresses are used at Layer 2 for local network communication.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Transport layer (Layer 4)
- ✗
Physical layer (Layer 1)
Why it's wrong here
Layer 1 deals with bits, cables, and hubs, not MAC addresses.
- ✗
Network layer (Layer 3)
Why it's wrong here
Layer 3 uses IP addresses, not MAC addresses.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that MAC addresses belong to the Network layer because they are used in routing decisions, but the trap is that MAC addresses are strictly a Data Link layer construct used for local segment delivery, not for end-to-end path determination.
Detailed technical explanation
How to think about this question
The Address Resolution Protocol (ARP) operates at the boundary of Layer 2 and Layer 3, mapping an IPv4 address to a MAC address. When a host needs to send a packet to a next-hop router, it first checks its ARP cache; if no entry exists, it broadcasts an ARP request (destination MAC FF:FF:FF:FF:FF:FF) to resolve the router's IP to its MAC. In IPv6, this function is performed by Neighbor Discovery Protocol (NDP) using ICMPv6 messages, which also operates at Layer 2.
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 practitioner preparing for the 200-901 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
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.
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FAQ
Questions learners often ask
What does this 200-901 question test?
Network Fundamentals — This question tests Network Fundamentals — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Data Link layer (Layer 2) — The MAC address of the next-hop router is found in the Data Link layer (Layer 2) header of a frame. When a device sends an IP packet to a next-hop router on the same segment, it encapsulates the packet in a frame with the destination MAC address of that router's interface. To verify this address, you examine Layer 2 information, such as by using the `show arp` command on Cisco devices to view the MAC-to-IP mapping.
What should I do if I get this 200-901 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
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Last reviewed: Jul 4, 2026
This 200-901 practice question is part of Courseiva's free Cisco 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 200-901 exam.
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