How is mac address unique

Viewed 1k times. Keith Keith 51 1 1 silver badge 9 9 bronze badges. When devices are manufactured properly, MAC addresses are globally unique. JonathonReinhart Just to make sure that I understand you. Absolutely not. Every Ethernet adapter ever made should have a unique MAC address, not found on any Ethernet adapter anywhere else on the planet.

Note that even though each port has a unique address, most systems allow overriding the configured MAC address from the OS. Add a comment.

Active Oldest Votes. Strictly speaking, it is only addresses without the locally administered bit set which are guaranteed to be unique. Those with that bit set could be made by whatever method someone chose, so there is a potential for collision. Steph4Net Steph4Net 11 1 1 bronze badge. Sign up or log in Sign up using Google. Sign up using Facebook. However, there are some valid reasons to want to change your MAC address. Some ISPs, typically cable modem providers, sell Internet subscriptions on a per-address basis.

Occasionally the ISP manages these subscriptions by assigning a static fixed IP address to the customer. However, this approach is an inefficient use of IP addresses that are currently in short supply. This device could be a broadband modem, for example. The customer is free to build a home or small business network behind this modem, but the ISP expects the MAC address to match the registered value at all times. Whenever a customer replaces their modem or adds a broadband router, the MAC address will no longer match that registered at the ISP, and the ISP will disable the customer's Internet connection.

One way to solve this problem is to call the ISP and ask them to update the registered MAC address to match the new hardware. A more efficient way to solve this problem is to configure the device so that it advertises the original MAC address, even though it's hardware is built to utilize a different MAC address. This process is called cloning. Many broadband routers today support MAC address cloning as an advanced configuration option. The exact procedure varies depending on the type of router.

However, in this case, cloning is not required. It's true that changing network adapters usually causes the cable modem connection to fail. To remedy this problem, though, requires only that the cable modem and computer be reset and perhaps a waiting period for the ISP to release the old IP address. This feature relies on software support built into the adapter driver program and thus does not work for all adapters. Likewise, the ifconfig command available in Linux and other flavors of Unix supports changing MAC addresses with the necessary network card and driver support.

The MAC address is an important element of computer networking. Of if you installed windows 10 on it and activated it then the hardware profile of your laptop might be stored somewhere. Still no hard proof. But better than going by MAC. The hardware MAC address is unique to the network card, and can not be changed.

The first three represent the manufacturer that made the card. The second three are supposed to make it unique. Typically it is increment by 1 for each NIC that rolls of the assembly line. Also note that some network cards are part of the motherboard, and some are add-in cards.

The network cards that are add-in cards can easily be swapped. It it important to know what kind it is because if I was a thief I would throw away the add-in card and use another one. However, most are not that smart, but any lawyer could argue that point. Almost, if not all, laptops have serial numbers and having that would help your case.

If you went through the tedious process of registering the laptop when you bought it then the manufacturer or retailer may have this number on file.

Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. Is a MAC address unique? Asked 3 years, 7 months ago. Active 1 year, 5 months ago. Viewed 6k times.

Improve this question. Ramhound Mark Mark 21 1 1 silver badge 2 2 bronze badges. You buy a Wi-Fi dongle? You have an Ethernet port built it? But it can be used to claim a device is yours.