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Introduction to Network Interface Cards (NICs) and MAC Addresses

CCNA: 0 to Hero - Comprehensive Network Engineering Bootcamp

Lesson 7: NICs and MAC Addresses

The Network Interface Card (NIC)

The NIC is the physical hardware component that allows a device (host, server, router) to connect to a network medium. Every device requires a NIC (or wireless adapter) to participate in a network.

MAC Addresses (Layer 2 Addressing)

The Media Access Control (MAC) address is a physical address assigned to the NIC by the manufacturer. It is a 48-bit address, typically represented in hexadecimal format (e.g., AA:BB:CC:11:22:33).

MAC Address Structure:

  • The first 24 bits are the OUI (Organizationally Unique Identifier), identifying the manufacturer (Cisco, Intel, etc.).
  • The last 24 bits are the Vendor Assigned Identifier, a unique serial number for the device.

Key Characteristics:

  • MAC addresses are used for local delivery within a single network segment (Layer 2).
  • They are supposed to be globally unique (burned-in address or BIA).

Practical Check (Windows/Linux)

To view your MAC address on Windows, use the command: bash ipconfig /all

On Linux/macOS, use: bash ip a