Suggest an editImprove this articleRefine the answer for “Why are MAC addresses needed?”. Your changes go to moderation before they’re published.Approval requiredContentWhat you’re changing🇺🇸EN🇺🇦UAPreviewTitle (EN)Short answer (EN)**MAC addresses** are needed to deliver data between devices within a single local network (LAN) at the data link layer of the OSI model. **Key point:** a MAC address handles frame delivery at L2, while an IP address handles routing at L3; they complement each other rather than replacing one another.Shown above the full answer for quick recall.Answer (EN)Image**MAC addresses are needed to deliver data between devices within a single local network (LAN)** at the data link layer of the OSI model. More simply, and to the point: **a MAC address determines which specific network device a frame is intended for within a single network**. --- ## Main reasons why MAC addresses are needed ### 1. **Addressing at the data link layer** A MAC address: - uniquely identifies a network interface - is used in every Ethernet / Wi-Fi frame - allows specifying the **sender and recipient** Without MAC addresses: - frames could not be delivered by address - the network would turn into "blind broadcasting" --- ### 2. **How switches work** Switches use MAC addresses to: - remember **which MAC is behind which port** - send frames **only to the right port** - avoid flooding data across the whole network unnecessarily This makes the network: - faster - more efficient - less congested --- ### 3. **Delivering data within a single network** MAC addresses work: - **only within a single local network** - **up to the first router** When the data goes further: - the old frame is discarded - a new frame is created with **different MAC addresses** --- ### 4. **Linking IP and the physical network** An IP address: - is logical - is used for routing between networks A MAC address: - is physical (data link) - is needed to actually deliver data **over a wire or through the air** The ARP protocol exists precisely to: - map an IP address to a MAC address --- ### 5. **Supporting different delivery types** MAC addresses make it possible to implement: - **unicast**: to one device - **multicast**: to a group of devices - **broadcast**: to all devices on the network Without MAC addresses these modes would be impossible. --- ## What's important to remember for an interview - A MAC address: - is used at the **data link layer (L2)** - is needed for **delivering frames** - An IP address: - is used at the **network layer (L3)** - is needed for **routing** They **do not replace** each other, they **complement** each other.For the reviewerNote to the moderator (optional)Visible only to the moderator. Helps review go faster.