What is MAC Address?

A MAC address (Media Access Control address) is a unique identifier assigned to the network interface card (NIC) of a device for use in network communications. It is used in local networks to ensure that data is sent to the correct device.

Key Points About MAC Address:

1. Format:
   • A MAC address is typically represented as a 12-digit hexadecimal number, often displayed in pairs separated by colons or hyphens.
   • Example: 00:1A:2B:3C:4D:5E
2. Structure:
   • The MAC address is 48 bits long (6 bytes).
   • The first 3 bytes (24 bits) are assigned to the manufacturer of the device (known as the Organizationally Unique Identifier (OUI)).
   • The last 3 bytes (24 bits) are assigned to the device itself, providing a unique identifier for each piece of hardware.
3. Function:
   • The primary role of a MAC address is to ensure that devices on a local network can identify each other and communicate with each other.
   • It operates at the Data Link Layer (Layer 2) of the OSI model, handling communication between devices on the same local network.
4. Static vs Dynamic:
   • Static (Burned-in): The MAC address is typically burned into the device’s hardware and cannot be changed. This ensures that every network interface card has a globally unique MAC address.
   • Dynamic: Some devices (especially in virtualized environments or network emulation) may have the ability to change or randomize their MAC addresses.
5. Usage:
   • In Ethernet Networks: Devices use MAC addresses to identify each other and transfer data over a network. When a device sends a data packet, the destination device’s MAC address is used to route the packet.
   • Wi-Fi Networks: MAC addresses are also used in Wi-Fi to connect to routers and other devices on wireless networks.
6. Difference from IP Address:
   • While IP addresses are used to identify devices on a global scale (across the internet), MAC addresses are used for local network communication.
   • IP addresses can change depending on the network or location, while MAC addresses are permanent for each device (unless altered manually in some cases).
7. Finding the MAC Address:
   • On Windows: Open Command Prompt and type ipconfig /all. Look for the “Physical Address” field under your network adapter.
   • On MacOS: Go to System Preferences > Network, select your active network connection, and click on Advanced. The MAC address will be displayed there.
   • On Linux: Use the command ifconfig or ip link show to find the MAC address.

Example Use Cases:

• Network Security: Network administrators can use MAC address filtering to allow or deny access to a network based on the MAC addresses of the devices trying to connect.
• Device Identification: In a local network, the MAC address helps identify and track devices, even if they change their IP address.
• Ethernet Frame Delivery: MAC addresses ensure that data frames are delivered to the correct network interface on a local area network (LAN).

Conclusion:

A MAC address is a hardware address that uniquely identifies devices within a local network, ensuring proper communication between them. It is an essential part of network protocols and is different from the IP address used for routing packets over the internet.