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Do MAC addresses change?

P

Phoenix

Member
Okay, now I know this is likely gonna be a stupid question. lol 😱 but since I'm relatively new with network's and nic's since a couple of months ago I signed up for cable modem service from my local cable company. 🙂

The reason I ask if the MAC adresses change is because RECENTLY I upgraded my video card and decided to watch what irq's went where since I also removed some other add on cards that I no longer needed. Anyways, my nic and my video card are BOTH using the same IRQ 11, which with windows irq steering isn't much of a problem but usualy when I get an instant message from AIM it cause's things to freeze for half a second. I am planning on moving the card to another pci slot so it has its own irq. But I wanted to know if the mac address changes and what not.

-Phoenix-

P.S. No I'm not new to computers, he he. Just never had an opportunity to play with networks.
 
The mac address is part of the NIC, He would only see a different MAC address if he put in a different NIC. Even if you did change cards a different MAC address at the NIC should not matter. The cable modem's MAC address is the one registered at your ISP.
 
Okay first things first. Thank Your guys for your replys.

Russ: Figured that was the case that each MAC address was card specific and didn't change when removed and put in another slot.


Lowtech: Yes, with a new NIC I expected the MAC address to change just since this is my first time playing with network stuff I had no clue whether or not a simple slot change could force the card to a new MAC address.

Wik: Your statement makes my line of thinking correct. 😀 BUT you say my cable modems MAC address is what my isp locks on to/registered at? Might be true but I doubt it, from what I have heard (not saying its 100% accurate) it seems as though the cable modem stores the NIC's MAC address and uses that as your verifaction to use the service. Plus, I saw the installer make a point of getting my MAC address written down on my forms. But thats neither here nor there, if and when I decide to change the NIC or add a router at a later date I will be sure to make sure the one I choose can SPOOF this cards mac address to save me some trouble. 🙂

Once again guys thank you for your help with this information
 
You should be able to tell the ISP the MAC addy of the new card and they'll take care of it. Unless they're total bastards.
 
Yes, you can change the MAC address within the NIC driver, but depends on NIC and driver.

Also called LAA (locally administered address) or DLC. Word to the WISE - you will never need to change your MAC address...don't mess with it, some ranges are reserved for broadcast and multicast applications and could cause you NIC to malfunction.

 
Doesn't it depend on the card more than the driver? The card would have to flash in the new mac or something wouldn't it? You couldn't just write a driver that fooled the card into overriding the hardcoded mac, could you?
 
I don't know much about changing MAC addresses, but it brings the question of what number could you change it to?

Unless each card had a set of numbers that it could use, I think that a random change would risk having two cards with the same address sometime, somewhere.

It seems wasteful.
 
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