Suggest an editImprove this articleRefine the answer for “What is a network switch (switch)?”. Your changes go to moderation before they’re published.Approval requiredContentWhat you’re changing🇺🇸EN🇺🇦UAPreviewTitle (EN)Short answer (EN)**A switch** is a data link layer (L2) network device that connects devices within a local network and forwards Ethernet frames based on MAC addresses. **Key point:** a switch learns MAC addresses in its MAC table (CAM table) and delivers a frame specifically to the device it is intended for, unlike a hub, which floods it to everyone.Shown above the full answer for quick recall.Answer (EN)Image**A switch** is a **data link layer (L2) network device** that **connects devices within a local network and forwards Ethernet frames based on MAC addresses**. Briefly and precisely: **a switch delivers frames specifically to the device they are intended for**, not to everyone at once. --- ## What a switch does ### 1. **Receives Ethernet frames** The switch receives a frame on one of its ports and **analyzes the MAC addresses** in the frame header. --- ### 2. **Learns MAC addresses (learning)** The switch remembers: - the **source MAC address** - the **port** the frame arrived on This information is stored in the **MAC table (CAM table)**. --- ### 3. **Decides where to send the frame** Based on the destination MAC address, the switch: - finds the matching port in the MAC table - **sends the frame only to the right port** If the destination MAC address is unknown: - the frame is temporarily flooded to all ports - after a reply, the table is updated --- ### 4. **Reduces the load on the network** Because of targeted delivery: - the amount of unnecessary traffic decreases - network performance improves - the chance of collisions is reduced --- ## What layer a switch operates at - Its main mode of operation: **the data link layer (L2)** - It works with: - Ethernet frames - MAC addresses Some switches can also operate at L3 (a Layer 3 switch), but a **classic switch is an L2 device**. --- ## What a switch does NOT do Important for an interview: A switch: - does not work with IP addresses (in basic mode) - does not route traffic between networks - does not analyze TCP/UDP ports - does not make application-layer decisions --- ## Difference from a hub (briefly) - A **hub** floods everything to all ports - A **switch** sends a frame only where the matching MAC address is locatedFor the reviewerNote to the moderator (optional)Visible only to the moderator. Helps review go faster.