Hdd Cloning And Mac Address

[rono]

after I have cloned a hard disk to another one I notice that both have the same mac address, I run regedit and change computer name, I also change the ip address in the network connections but the mac address is still the same.

I have done this cloning many times with many computers and most of the times the mac address will correct itself, sometimes it doesn't.

How come and what can I do about that mac address to have a unique one

[dudemeister]

Isnt the mac address hard coded and unique to the NIC/network card.

[robblok]

Isnt the mac address hard coded and unique to the NIC/network card.

I never heard of a mac adress on a harddisk.. unless its a NAS drive (but im not sure about that one)

[rono]

I have several computers lan connected, each computer has a name let's say comp1, comp2....this name is to be found in the run regedit command h key local machine etc..the are no computer name files that have to be changed from comp2 to comp1 after I cloned 2 to 1.

furthermore: in network connections I will have to open tcp/ip and also change the ip address there from 192.xxx.x.102 to 192.xxx.1.101.

I have software on my main pc allowing me to see the activity on each pc, this software also shows me the pc name (1-2..) his ip address (192.xxx.1.101-102...) and his mac address.

Now I recently cloned 2 hdd and a 3 of them showed the same mac address and this gives a conflict, the mac address is in the windows software so if you clone a HDD you also copy the addresses.

now usually after a restart these mac addresses sort themselves out, sometimes they don't and this is a problem

[welo]

OP has probably cloned a harddisk including a system partition (Windows I assume).

The MAC address is device specific (specific to the network device) and usually unique. The Mac address is used during communication on a network but on a lower level (aka OSI layer) than the IP address.

Every network card (wireless or not) ships with a unique MAC address 'built-in'.

Many network devices resp. their drivers support overriding this built-in MAC address (REALTEK based cards usually do). In Windows goto Device Manager, find the network card, select properties and switch to the 'Advanced Properties' tab. There is a list of properties, one might say MAC address or similar. Note that not all network cards / drivers support this feature. I assume that with some cards no option might show up in Device Manager but you might still be able to change it using a vendor specific tool.

In a standard Windows setup the built-in MAC address is used. Windows should not 'hardwire' the MAC address or store it anywhere. I am surprised that after cloning Windows remembers the MAC address and does not 'read' the built-in address of the new network card.

Possible explanations:

• OP was overriding the built-in MAC address in the original setup, and this override is still active on the cloned system
  
• The network driver somehow stores the MAC address and doesn't 'notice' that the underlying network card has changed
  
• Windows works somehow different than I expect.
  

Possible solution

• Make sure you don't 'override' the MAC address before cloning or remove the override on the cloned system
  
• Maybe removing the device in Device Manager and re-installing the device will fix the problem
  

welo

[astral]

Isnt the mac address hard coded and unique to the NIC/network card.

That is the theory, but in Windows the MAC address is also held in the SW (memory?)

and can be changed.

Useful if your ISP checks the MAC address and you want to use a different computer, or change the network card.

[swifter]

The MAC address is hard coded into a chip on the network card. In addition to being a unique identifier, the first series of numbers are manufacturer specific.

However...

MAC addresses can be "spoofed", and if your operating system is running a virtual bridge device or a virtual operating system (with virtual network devices), those MAC addresses are arbitrarily assigned by the operating system, not retrieved from any physical chipset.

Regarding NAS devices, the same rules apply. The storage units physical network interface provides the MAC address, at least with copper lines.. although Ive seen NAS solutions which had virtual NICs which had OS-generated MAC addresses.

[swifter]

Isnt the mac address hard coded and unique to the NIC/network card.

That is the theory, but in Windows the MAC address is also held in the SW (memory?)

and can be changed.

Useful if your ISP checks the MAC address and you want to use a different computer, or change the network card.

At the risk of over complicating the discussion, although you can change the MAC address on the OS layer, and present that MAC over the network, software running on your computer can query the card directly to retrieve the hard-coded MAC address. Online-poker software and other borderline-spyware employs this tactic, for example.