Know and understand common network devices including network interface cards (NIC), hubs, bridges, and switches.
1. Network Interface Card (NIC)
A NIC is a hardware component that connects a computer or other device to a network. It provides the physical interface and implements the data link layer protocols required for communication.
Usually built into the motherboard or added as an expansion card.
Provides a unique MAC address for each device.
Supports various media types (Ethernet, Wi‑Fi, fiber).
Handles framing, error detection, and sometimes basic flow control.
2. Hub
A hub is a simple networking device that connects multiple Ethernet devices together, making them act as a single network segment.
Operates at Layer 1 (Physical layer) of the OSI model.
Broadcasts incoming data to all ports; no intelligence to direct traffic.
Creates a single collision domain – only one device can successfully transmit at a time.
Easy to install but inefficient for larger networks.
3. Bridge
A bridge connects two separate network segments, allowing them to function as a single network while reducing collisions.
Operates at Layer 2 (Data Link layer).
Filters traffic based on MAC addresses; forwards frames only to the segment where the destination resides.
Creates separate collision domains for each segment, improving performance.
Often used to connect different media types (e.g., Ethernet to Wi‑Fi).
4. Switch
A switch is a multi‑port network device that intelligently forwards data to the correct destination device.
Operates at Layer 2, with some models also providing Layer 3 (routing) functions.
Maintains a MAC address table to map ports to devices.
Each port is its own collision domain, allowing full‑duplex communication.
Supports features such as \cdot LANs, link aggregation, and QoS.
Comparison of Common Network Devices
Device
OSI Layer
Function
Collision Domain
Typical Use
NIC
Layer 1 & 2
Provides physical and data‑link connectivity for a single device
One per device
End‑point connection to a network
Hub
Layer 1
Repeats incoming signals to all ports
All ports share one domain
Small, simple networks (legacy)
Bridge
Layer 2
Filters and forwards frames between two segments
Two separate domains (one per segment)
Connecting dissimilar media or isolating traffic
Switch
Layer 2 (some Layer 3)
Intelligently forwards frames to the correct port
One per port (full‑duplex)
Modern LANs, office and campus networks
Key Points to Remember
Every device on a network needs a NIC to communicate.
Hubs are simple but cause many collisions; they are largely replaced by switches.
Bridges reduce collisions by segmenting networks and only forwarding necessary traffic.
Switches provide the most efficient traffic handling, giving each port its own collision domain and supporting advanced features.
Suggested diagram: A schematic showing a NIC in a PC connected to a switch, with other devices (another PC, a printer) also linked to the switch; include a hub and a bridge in separate sections for contrast.