IP Address & MAC Address Binding

IP Address

• Definition: A logical identifier assigned to a device in a network (IPv4 or IPv6).
• Role: Used for communication across networks.
• Changeable: Can be reassigned (static or dynamic via DHCP).

MAC Address

• Definition: A Media Access Control (MAC) address is a unique hardware identifier burned into a network interface card (NIC).
• Format: 48‑bit hexadecimal (e.g., 00:1A:2B:3C:4D:5E).
• Role: Used at the data link layer to physically identify a device on a local network.
• Permanent: Usually fixed to the hardware (though it can be spoofed).

IP–MAC Binding

• Definition: The process of associating a specific IP address with a specific MAC address.
• Purpose: Ensures that a device always gets the same IP address, and prevents IP conflicts or spoofing.
• How it works:
  • In DHCP servers, you can create a reservation: when a device with MAC 00:1A:2B:3C:4D:5E connects, it always receives IP 192.168.1.100.
  • In routers, IP–MAC binding can also be used as a security feature to prevent unauthorized devices from claiming an IP.

Example

• Home network: Router binds your printer’s MAC address to IP 192.168.1.50, so it’s always reachable at that address.
• Enterprise network: DHCP server reserves IPs for critical servers based on their MAC addresses.
• Security setup: Router blocks traffic if a device tries to use an IP not bound to its MAC.

Benefits

• Consistency: Devices like printers, servers, or cameras always have the same IP.
• Security: Prevents IP spoofing (a malicious device pretending to be another).
• Network stability: Avoids IP conflicts in DHCP environments.
• Access control: Admins can restrict which MAC addresses are allowed to use certain IPs.

Summary

• IP address = logical, can change.
• MAC address = physical, unique to hardware.
• IP–MAC binding = ties them together for consistency and security. It’s widely used in DHCP reservations and router security features.