200-901 Network Fundamentals Practice Question
At which layer of the OSI model do switches operate when forwarding frames based on MAC 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
✓
Layer 2 (Data Link)
Switches operate at Layer 2 (Data Link layer) because they use MAC addresses to forward frames.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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Layer 1 (Physical)
Why it's wrong here
Layer 1 concerns bits, voltages and physical media; MAC-address forwarding is a data-link function, so physical-layer devices such as repeaters and hubs cannot read frame headers. It is tempting because switches have physical ports and cabling, and Layer 1 would be the answer for signal regeneration.
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Layer 3 (Network)
Why it's wrong here
Forwarding frames by MAC address is Layer 2 switching, since MAC addressing and frame delivery sit at the data-link layer. Layer 3 forwarding instead uses IP addresses and routing tables, which is what a router or multilayer switch does when routing between subnets.
- ✓
Layer 2 (Data Link)
Why this is correct
Switches forward frames using MAC addresses contained in Ethernet headers, which reside at Layer 2, the Data Link layer. This satisfies the scenario's forwarding basis, distinguishing switches from Layer 3 routers that forward on IP addresses.
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Layer 4 (Transport)
Why it's wrong here
Layer 4 handles end-to-end transport with TCP and UDP port numbers, and switches forwarding on MAC addresses never inspect those headers. It is tempting because Layer 4 load balancers also direct traffic, and Layer 4 would be correct for port-based distribution rather than frame forwarding.
Quick reference
Access Control Model Comparison
| Model | Acronym | Who Controls Access? | Best For |
|---|---|---|---|
| Discretionary Access Control | DAC | Resource owner | Small teams, file shares |
| Mandatory Access Control | MAC | System / security labels | Classified govt / military |
| Role-Based Access Control | RBAC | Administrator (via roles) | Enterprise environments |
| Attribute-Based Access Control | ABAC | Policy engine (user + resource attributes) | Fine-grained, dynamic policies |
| Rule-Based Access Control | RuBAC | System rules / ACLs | Firewall rules, network ACLs |
Go deeper
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.