mac address 00-00-00-00-00-00 on my network card - what does this mean?

I've been troubleshooting some problems with my cable modem connection.  In the process, I discovered that my Windows XP Pro computer is reading my network card's MAC address as 00-00-00-00-00-00.  This is invalid, right?  What does this mean?  My network connection seems to work fine, but I do have some intermittent connection issues and I'm wondering if this could be related.  I tried changing the MAC address (I have the option to do so when I go into properties on the network card).  

The card is listed as SiS 900-Based PCI Fast Ethernet Adapter.  If I look at the properties and click the advanced tab, I have the option of setting a value for "NetworkAddress".  If set to the "not present" option, I get 00-00-00-00-00-00.  I tried changing it to 11-11-11-11-11-11 and that worked but I lost my internet connection.  I think the change confused my router.  

Anyway, I'm wondering what I should the card I need to take it out and see if there is an address listed on it...should I just change it to some other value???  I'm open to suggestions - this is kind of a weird thing and I'm not sure what the implications are.

Who is Participating?

Improve company productivity with a Business Account.Sign Up

SuperCoreyConnect With a Mentor Commented:
This sounds a little like a problem I had with some Asus boards a while back, Windows XP would automatically pick up the network card drivers, but because of ASIC changes by Asus, the default Windows XP driver would not pickup the MAC address properly. Basically the fix for this was to install the NIC drivers again from the motherboard CD, or updated ones from Asus.

I would definately give reinstalling the NIC drivers a whirl.

The only other thing that I can think of off the top of my head would be if you had a router and used the "Clone MAC Address" feature and then had the WAN port on the router hooked into the LAN.

At worst, throw another network card in for the 5 bucks that they are today and see what happens.
publicConnect With a Mentor Commented:
Sis 900 is not a card, but an embedded motherboard controller. You can download a utility from the mobo manufacturer, for example ECS, or from sis to set the mac address.
Also the mobo usually has a sticker on one of the connectors listing the mac.
Keep up with what's happening at Experts Exchange!

Sign up to receive Decoded, a new monthly digest with product updates, feature release info, continuing education opportunities, and more.

You cannot change the mac address of a NIC card.  It is an embedded address stamped onto the board.  Every manufacturer has a few hexadecimal digits in the mac address that identify the make, and the last ones are the serial number so to speak for that card.  This way no 2 cards are EVER the same mac address.  if we could change the mac address Layer 2 and layer 3 devices such as switches or routers would have such confusion it wouldnt work.
wendy326Author Commented:
Sorry for the delay in responding...I got a little too busy to troubleshoot.  However, I just downloaded the latest SIS driver for the chipset on my motherboard, and voila!  I have a MAC address now.  Magic.

Thanks for the help...I'm going to split points between supercorey for suggesting a reinstall of the drivers, and for public for suggesting how to find them and reminding me the lan was on the mobo.  I'm thrilled I didn't have to bother opening up the machine.  

You guys are great!

sorry hey was going through your q - where did yu download the driver from? I have similar problem with a laptop who's CD-ROM drive won't work and I can't connect to the network
wendy326Author Commented:
I had to figure out who made the chipset on my motherboard that had the lan on it.  Then I went to their website to get the driver.  You might try the website for your laptop manufacturer.  Good luck.
thanx hey. will need your luck too
Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

All Courses

From novice to tech pro — start learning today.