MAC Address
What is a MAC Address?
A MAC Address (Media Access Control Address) is a unique hardware identifier assigned to every network interface such as a mobile phone, laptop, Wi-Fi card, or Ethernet card.
- It is stored permanently in the network hardware
- Assigned by the device manufacturer (Intel, Broadcom, Qualcomm, etc.)
- Example format:
00:1A:2B:3C:4D:5E
A MAC address can be thought of as the fingerprint of a device within a local network.
Why is a MAC Address Used?
MAC addresses are used to identify devices inside a local network (LAN) and to ensure data reaches the correct physical device.
Main uses:
- Identifying devices in a local network
- Helping switches forward data to the correct port
- Supporting DHCP for IP address assignment
- Network security (MAC filtering)
Without MAC addresses, local network communication is not possible
Where Does a MAC Address Work?
A MAC address operates at Layer 2 (Data Link Layer) of the OSI Model.
It is used in:
- Home Wi-Fi networks
- Office LANs
- Network switches
- ARP (IP to MAC resolution)
- DHCP reservations
⚠️ Important:
- MAC addresses do not travel across the internet
- They are only valid within the local network
How Does a MAC Address Work?
Example:
- Laptop A wants to send data to Laptop B
- Both devices are connected to the same Wi-Fi network
Step-by-step flow:
- Laptop A knows the IP address of Laptop B
- Laptop A uses ARP to ask:
“What is the MAC address of this IP?”
- Laptop B replies with its MAC address
- Laptop A sends data using:
- Destination MAC = Laptop B’s MAC address
- The switch forwards the data based on the MAC address
Why is a MAC Address Important?
MAC addresses are important because:
- Network switches work using MAC addresses, not IPs
- Local data delivery is impossible without MAC addresses
- They help in network troubleshooting
- Enable device-level security controls
- Provide a stable identity for a device
IP addresses can change, but MAC addresses usually remain the same
MAC Address vs IP Address
| Feature |
MAC Address |
IP Address |
| Type |
Hardware address |
Logical address |
| OSI Layer |
Layer 2 (Data Link) |
Layer 3 (Network) |
| Assigned by |
Manufacturer |
Router / ISP |
| Changes? |
Rarely |
Frequently |
| Scope |
Local network only |
Local + Internet |
| Example |
00:1A:2B:3C:4D:5E |
192.168.1.10 |
Simple analogy:
- IP Address = Home address
- MAC Address = Room number inside the home
Delivery process:
- Reach the house → IP address
- Reach the correct room → MAC address