Switching is a core concept in computer networking and one of the most common topics asked in network engineer interviews. Almost every local area network relies on switching to connect devices and allow smooth communication. Without switching, modern LANs would be slow, noisy, and inefficient.
Network switching focuses on how data is forwarded inside a network using switches. These switches use MAC addresses to make intelligent decisions about where data should go. In this blog, you will understand network switching in a simple, interview-friendly way, with clear explanations and practical examples. The content is designed to help beginners as well as professionals preparing for networking interviews.
Interview Questions and Answers on Switching in Networking
Question 1: What is switching in networking?
Answer: Switching in networking is the process of forwarding data frames between devices within the same network. A switch receives data from one device and sends it directly to the intended destination device using MAC addresses. This makes communication faster and more efficient compared to broadcasting data to all devices.
Question 2: What is network switching used for?
Answer: Network switching is used to connect multiple devices within a local area network and manage data traffic between them. It ensures that data reaches the correct device while reducing unnecessary traffic, collisions, and delays.
Question 3: What is a network switch?
Answer: A network switch is a networking device that connects multiple devices such as computers, servers, and printers within a LAN. It forwards data based on MAC addresses and operates mainly at the Data Link Layer of the OSI model.
Question 4: What is a MAC address table?
Answer: A MAC address table is a table maintained by a Layer 2 switch that maps MAC addresses to physical switch ports. It allows the switch to forward data efficiently without flooding the entire network.
Question 5: What happens if a destination MAC address is not found in the MAC table?
Answer: If the destination MAC address is not found, the switch floods the frame to all ports except the source port. Once the destination device responds, the switch learns its MAC address and updates the MAC address table.
Question 6: What is a Layer 2 switch?
Answer: A Layer 2 switch operates at the Data Link Layer of the OSI model. It forwards data using MAC addresses and does not perform routing based on IP addresses. Layer 2 switches are commonly used in LAN environments.
Question 7: What is LAN switching?
Answer: LAN switching refers to the use of switches to connect devices within a local area network. It enables fast, reliable, and collision-free communication between devices by forwarding data only where it is needed.
Question 8: What is the difference between a switch and a hub?
Answer: A hub broadcasts incoming data to all connected devices, regardless of the destination. A switch forwards data only to the intended device using MAC addresses. This makes switches more efficient, secure, and faster than hubs.
Question 9: Why is switch vs hub a common interview topic?
Answer: Switch vs hub is commonly asked because it clearly demonstrates understanding of basic networking concepts like collision domains, broadcast behavior, and performance differences in LAN switching.
Question 10: What are the main types of switching?
Answer: The main types of switching are circuit switching, packet switching, and frame switching. Ethernet-based LAN switching is an example of frame switching.
Question 11: What is store-and-forward switching?
Answer: Store-and-forward switching is a method where the switch receives the complete frame, checks it for errors, and then forwards it to the destination. This improves reliability but introduces slight latency.
Question 12: What is cut-through switching?
Answer: Cut-through switching forwards a frame as soon as the destination MAC address is read. It reduces latency but may forward corrupted frames since error checking is minimal.
Question 13: What is fragment-free switching?
Answer: Fragment-free switching is a hybrid approach where the switch reads the first part of the frame before forwarding it. This helps avoid forwarding frames with collisions while keeping latency low.
Question 14: What are VLANs in switching?
Answer: VLANs (Virtual Local Area Networks) logically divide a physical network into multiple broadcast domains. VLANs improve security, reduce broadcast traffic, and enhance network performance.
Question 15: What is trunking in switching?
Answer: Trunking allows multiple VLANs to pass over a single physical link between switches. VLAN tagging is used so the receiving switch knows which VLAN the traffic belongs to.
Question 16: How does switching improve network performance?
Answer: Switching improves performance by reducing collisions, minimizing broadcast traffic, enabling full-duplex communication, and isolating traffic using VLANs.
Question 17: How is switching related to the OSI model?
Answer: Switching primarily operates at the Data Link Layer (Layer 2) of the OSI model. Some advanced switches also operate at Layer 3, combining switching and routing capabilities.
Question 18: What is the difference between switching and routing?
Answer: Switching forwards data within the same network using MAC addresses, while routing forwards data between different networks using IP addresses.
Question 19: What is Layer 3 switching?
Answer: Layer 3 switching combines traditional switching with routing. These switches can forward traffic based on both MAC and IP addresses and are commonly used in large enterprise networks.
Question 20: What are common switching issues?
Answer: Common switching issues include MAC address table overflow, VLAN misconfiguration, incorrect trunk settings, and network loops without proper loop prevention.
Conclusion
Switching is the backbone of local area networking and a critical concept for anyone learning computer networking. By understanding how network switching works, how Layer 2 switches use MAC address tables, and how switches differ from hubs, you build a strong foundation for interviews and real-world networking tasks. Concepts like LAN switching, VLANs, trunking, and Layer 3 switching are essential for designing and managing modern networks efficiently.
