Why might a computer have more than one MAC address?

Question

Why might a computer have more than one MAC (Media Access Control) address?

Suppose the output was from a computer that also had wireless Ethernet capability. How might the output change?

Answer 1

Each network card would have its own Mac address



So for instance A laptop that has Ethernet connection and a wireless card would have 2 Mac addreses



A PC with 2 Network cards would have 2 Mac addreses.

Answer 2

Each component (your non-wireless PCI card and your wireless card) BOTH have MAC addresses. I'm not sure I fully understand your question, what do you mean "output change", and how i that relevant to MAC address? MAC address is simply a unique ID to any given component.

Answer 3

This question was found at my CISCO course in almost exact words. Here are the questions in complete form:

"Why might a computer have more than one MAC (Media Access Control) address?



-------> The sample output from the ipconfig /all command shown previously had only one MAC address. (---> this part is missing in the original question shown in this thread) CISCO course had gave us a sample using ipconfig /all showing only one MAC address)



Suppose the output (---> meaning other MAC addresses showing in your screen...) was from a computer that also had wireless Ethernet capability. How might the output change?



The answer for the first question is YES, a computer can have more than one MAC (Media Access Control) address.



If we have wireless adapter, Bluetooth adapter, or even virtual machines installed in your computer, once you go to the command line interface and type the command ipconfig /all, it will show all the different MAC addresses.



What do the bits/bytes of each MAC address represent?

Every Ethernet network interface has a physical address assigned to it when it is manufactured. These addresses are 48 bit (6 bytes) long and are written in hexadecimal notation. MAC addresses are made up of two parts. One part of the MAC address, the first 3 bytes, represents the vendor who manufactured the network interface. This part of the MAC is called the OUI (Organizationally Unique Identifier). The second part of the address, the remaining 3 bytes are the unique ID for the interface. All MAC addresses that begin with the same OUI must have unique values in the last 3 bytes.



Why this is important?

When you go to your command line interface and type ipconfig /all, you might see more than 1 Physical Address which means MAC address. Example: XX-XX-XX-YY-YY-ZZ



The first 3 bytes called OUI can tell you who s the manufacturer by going to this site: https://www.wireshark.org/tools/oui-lookup.html



So... your first 3 bytes XX-XX-XX indicates who was the manufacturer, and the last 3 bytes YY-YY-ZZ will change for each VIRTUAL or PHYSICAL adapter. Let s say you have a Bluetooth adapter, a wireless adapter, and a few virtual machines running in your computer. They will all have different endings in your MAC address unless your Bluetooth adapter is from another manufacturer.



All virtual adapters will have the same OUI as the physical NIC.



I tried to be comprehensive in my answer just in case someone looks up for an answer to this question in the future.