CompTIA Network+ (N10-009)Networking ConceptsEasy
At which layer of the OSI model does a switch primarily operate when forwarding frames based on MAC addresses?
- ALayer 1 - Physical
- BLayer 3 - Network
- CLayer 4 - Transport
- DLayer 2 - Data Link
Show answer & explanationAnswer & explanation
Correct answer: D. Layer 2 - Data Link
Switches read the destination MAC address in the frame header to make forwarding decisions, which is a Data Link layer (Layer 2) function. Layer 3 devices like routers use IP addresses instead.
Why the other options are wrong
- A. Physical layer deals with bits and signals, not addressing.
- B. Layer 3 uses IP addresses, which is the router's job.
- C. Layer 4 handles ports and end-to-end connections, not frame forwarding.
Layer 2 Switching
Switches operate at the Data Link layer, using MAC address tables to forward frames only out the port where the destination device resides.
- Switches build a MAC address table by learning source addresses
- Unknown destination MACs are flooded out all ports except the source
- Layer 2 devices do not read IP addresses
Memory trick: Please Do Not Throw Sausage Pizza Away