Question 1

What is a MAC address and how does it work?

Accepted Answer

A MAC (Media Access Control) address is a unique 48-bit identifier assigned to network interfaces by manufacturers. Written as six pairs of hexadecimal digits (e.g., 00:1A:2B:3C:4D:5E), the first three octets identify the manufacturer (OUI), while the last three are device-specific. MAC addresses operate at Layer 2 of the OSI model for local network communication.

Question 2

What is an OUI in MAC addresses?

Accepted Answer

OUI (Organizationally Unique Identifier) comprises the first 24 bits of a MAC address, identifying the manufacturer. IEEE assigns OUIs to hardware vendors who then assign unique device IDs. Companies like Apple (3C:06:30), Cisco (00:1E:14), and Intel (00:50:56) have multiple registered OUIs. Lookup tools use IEEE's public OUI database for identification.

Question 3

Can MAC addresses be changed or spoofed?

Accepted Answer

Yes. While manufacturers assign MAC addresses, operating systems allow modification (MAC spoofing). This is useful for privacy, bypassing network restrictions, or testing. However, spoofing may violate network policies or laws in some jurisdictions. Most devices support changing MAC addresses through network settings or command-line tools, though some hardware has limitations.

Question 4

How do I find my device's MAC address?

Accepted Answer

Windows: Run "ipconfig /all" in Command Prompt, look for "Physical Address". Mac: System Preferences > Network > Advanced > Hardware, or run "ifconfig en0". Linux: Run "ip link show" or "ifconfig". Mobile devices: iOS Settings > General > About > Wi-Fi Address; Android Settings > About > Status > Wi-Fi MAC address. Each network interface has its own MAC.

Question 5

What are private and locally administered MAC addresses?

Accepted Answer

Locally administered MAC addresses have the second-least significant bit of the first octet set to 1 (e.g., x2, x6, xA, xE in first octet). These are not globally unique and can be assigned by network administrators. Since iOS 14 and Android 10, devices use randomized private MAC addresses for Wi-Fi networks to enhance privacy.

Question 6

Why is MAC address lookup important for security?

Accepted Answer

Security teams use MAC lookup for network inventory (identifying unauthorized devices), forensics (tracking device manufacturers), access control (MAC filtering), rogue device detection, and incident response. While MAC addresses can be spoofed, lookup helps establish baseline inventory and detect anomalies. Combine with other factors for robust security rather than relying solely on MAC filtering.

Question 7

What is the difference between MAC and IP addresses?

Accepted Answer

MAC addresses are hardware identifiers assigned by manufacturers, permanent (though changeable), and work at Layer 2 for local network communication. IP addresses are logical identifiers assigned by networks, temporary (DHCP) or static, and work at Layer 3 for routing across networks. Devices need both: MAC for local switching, IP for internet routing.

Question 8

How often is the IEEE OUI database updated?

Accepted Answer

IEEE updates the OUI database daily as manufacturers register new addresses. Public lookup tools should refresh their databases monthly minimum for accuracy. New device types (IoT, wearables) constantly emerge, requiring fresh assignments. The MA-L (24-bit OUI), MA-M (28-bit), and MA-S (36-bit) registries all receive regular updates from IEEE registration authority.

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