MAC Address vs. IP Address – Detailed Explanation
Definition of MAC Address
MAC Address stands for Media Access Control Address. It is a hardware-based, globally unique identifier assigned to a network interface card (NIC) by the manufacturer. It operates at Layer 2 (Data Link layer) of the OSI model.
Example: 00:1A:2B:3C:4D:5E
Definition of IP Address
IP Address stands for Internet Protocol Address. It is a logical (software-configurable) address assigned to devices for communication on a network. It operates at Layer 3 (Network layer) of the OSI model.
Examples:
- IPv4:
192.168.1.10 - IPv6:
2001:0db8:85a3::8a2e:0370:7334
Purpose and Function Differences
| Aspect | MAC Address | IP Address |
|---|---|---|
| Purpose | Identifies devices within the same local network | Identifies devices across different networks |
| Function | Enables frame delivery within the local segment | Enables packet routing between networks |
| Example | 00:1A:2B:3C:4D:5E | 192.168.1.10 |
Summary: MAC uniquely identifies physical devices on a LAN; IP provides addresses to devices in the broader network (local or global).
Address Format and Representation
| Address Type | Format | Example |
|---|---|---|
| MAC Address | 48-bit hexadecimal, six pairs separated by colons or hyphens | 00:1A:2B:3C:4D:5E |
| IP Address (IPv4) | 32-bit dotted decimal | 192.168.1.10 |
| IP Address (IPv6) | 128-bit hexadecimal, colon-separated groups | 2001:db8::1 |
Scope of Addressing
- MAC Address: Local network segment only; cannot route beyond LAN.
- IP Address: Local (private) or global (public); routable across multiple networks and the Internet.
How They Work Together – Process Example
Suppose John’s laptop (IP: 192.168.1.10, MAC: 00:1A:2B:3C:4D:5E) wants to send data to a printer (IP: 192.168.1.20, MAC: 00:1B:4C:7D:8E:9F):
- John’s laptop knows the printer’s IP but not its MAC.
- It sends an ARP request asking “Who has 192.168.1.20?”
- The printer replies with its MAC address.
- The laptop constructs an Ethernet frame with the printer’s MAC as destination.
- The frame is delivered within the LAN using MAC addresses; routers use IP addresses for routing between networks.
Key point: MAC addresses enable local delivery, IP addresses enable inter-network routing.
Static vs. Dynamic Assignment
| Address Type | Assignment | Typical Usage |
|---|---|---|
| MAC Address | Usually static, assigned by manufacturer (BIA); can be overridden (LAA) | Hardware identification |
| IP Address | Static (manual) or dynamic (DHCP) | Network communication |
Role in Network Communication
- MAC Address: Used by switches and bridges for frame forwarding within LANs.
- IP Address: Used by routers to route packets between LANs and across the Internet.
Security Implications
- MAC Spoofing: Attackers can fake MAC addresses to bypass controls. Mitigation includes port security and monitoring.
- IP Spoofing: Attackers forge IP source addresses to hide identity or launch attacks. Mitigated by filters, firewalls, IPS.
Why Both Matter
- Data Delivery: MAC addresses ensure correct frame delivery on LAN; IP addresses allow packets to travel across networks.
- Troubleshooting: Both MAC and IP addresses are crucial. Commands like
arp -ashow MAC-IP mappings;pingandtraceroutetest IP connectivity.
Exam Tips & Key Points
- MAC is physical, Layer 2; IP is logical, Layer 3.
- MAC addresses are fixed by default, IP addresses can be static or dynamic.
- MAC identifies devices locally; IP identifies devices globally or locally.
- Think of MAC as house address, IP as postal address across cities.
- ARP translates IP addresses to MAC for local delivery.
- Both must be correct for communication to succeed.
- Be aware of spoofing risks and mitigation techniques.
When and How to Use
- Assign IP addresses for network configuration; MAC addresses are hardware-defined but can be overridden if needed.
- Use MAC filtering for device-level access control (e.g., Wi-Fi).
- Use IP addresses for routing and network-wide communication.
- In troubleshooting, locate devices by MAC on switches, test connectivity by IP.