Quiz Entry - updated: 2026.07.14
What is the difference between Network Layer (L3) and Data Link Layer (L2) addresses?
L3 uses IP addresses to deliver the packet end-to-end (source to final destination, unchanged); L2 uses MAC addresses to deliver the frame one hop at a time and changes at every hop.
* IP is end-to-end and constant; MAC is hop-local and rewritten each hop. *
| Layer | Address Type | Purpose |
|---|---|---|
| Network Layer (L3) | IP Address | Delivers the IP packet from original source to final destination (global/end-to-end) |
| Data Link Layer (L2) | MAC Address | Delivers the frame from one NIC to another NIC on the same network (local/hop-to-hop) |
Key insight:
- L3 (IP) addresses remain the same throughout the journey
- L2 (MAC) addresses change at each hop as the frame moves between networks
Go deeper:
Host to Host through a Router — Practical Networking — shows the L3 header staying fixed while L2 is regenerated each hop.- MAC address — the Layer-2 address that only has meaning on one link.