EDIT: As commentor Brian points out, the media type for all Vista and beyond installations is the same. Media type was only different in XP and prior versions of Windows. The license key that was used to install Windows is what will now determine the channel ID. I’ve had a hard time tracking down documentation on this subject, so it’s a bit fuzzy. However, I still remain skeptical that the media files between OEM, TechNet and MSDN are completely identical in Vista and beyond. I have no proof of this though, and it remains to be tested if my suspicions are true.
Far too many times, I’ve troubleshot a Windows PC and come to find out that the image was made from media that did not match the license that I was trying to work with. Unfortunately, I know many IT Professionals that use MSDN or TechNet images in a pinch for production machines, and rationalize that “It’s the same bits, and I really do have the license for it, I just don’t have the right media at this moment.” That’s true, to an extent, but it’s still completely illegal and seems to have a technical detriment at times as well.
While Vista and beyond theoretically use the same media regardless of TechNet, OEM, Retail and etc, I still have my doubts. Nonetheless, the license key used to install Windows is still very important. Many times I have suspected that a TechNet or MSDN license was used to activate Windows in a production environment, but had no knowledge of how to discern the truth of the matter.
Was this PC installed from the MSDN image or license? Maybe an OEM disc that someone had laying around? Perhaps a Volume License image? I suspected that there was a way to tell, because in many instances certain Windows features didn’t behave like I thought they should when the image was from TechNet or MSDN. There seemed to be a way that Microsoft “just knew” that the image wasn’t from the media type that it should have been.
While I don’t know about any tell-tale signs deep in the Windows bits, I now know that there is a high level way of discerning a Windows image’s origins. Thanks to this ServerFault question “Which media was used to install Windows 7”
I saw it and decided to launch into an investigation. I had had that very question running through my mind many times, but could never get to the bottom of it. In fact, after sifting through a mountain of search engine results to try and answer the ServerFault question, I still couldn’t find an answer. I favorited the question with the hopes that someone would answer it in the coming weeks or months. Fortunately, I didn’t have to wait that long. The question’s author found the answer just a little while later.
The crux of the matter is within the Windows Product ID and how one interprets the numbers. A Windows Product ID looks like this: 12345-123-1234567-12345. Notice that the Product ID is not the Product Key, the latter being what you are essentially paying for when you buy Windows. Searching for information on how to find the Product ID comes back with plenty of misguided articles that confuse the two. Here’s Microsoft way of finding the Product ID for some of the most popular iterations of Windows.
You can also find the Windows Product ID at the following registry key: HKLMSOFTWAREMicrosoftWindows NTCurrentVersionProductId
Oddly, I found the Windows Product ID at this seemingly unrelated key: HKLMSOFTWAREMicrosoftInternet ExplorerRegistrationProductId
The major source of information for how to interpret the Product ID number is from a free tech support community (that I had not heard of before this topic came up) called LunarSoft at their Windows Product IDs page. Searching around for other sources of Windows Product ID information finds that everyone seems to be gathering their information from them, even answers on Microsoft’s own support forums will link back to their Product ID page. If anyone knows where the official Microsoft information can be found, let me know.
The key part of the Product ID that is important for discovering what image was used to install Windows is the “Channel ID” – the three digit number that is the second number in the four number PID. In my case, my Channel ID is 292, however that number isn’t on the list at LunarSoft. Apparently, while LunarSoft’s list is great, it is a bit dated. You can see this forum thread that makes mention of the outdated nature of the list.
There is still some confusion, but apparently 292 stands for Windows Ultimate Retail, which stands to reason since my installation is Windows Ultimate installed from a disc I scored for free at an official Windows 7 launch party in Pittsburgh. I think the list of Channel IDs is in need of some confirmation, but I can’t find any official documentation on the subject. However, between LunarSoft’s Windows Product ID page and the forum thread over at MyDigitalLife I think you should be mostly taken care of.
Once you have your Channel ID, compare it to either LunarSoft’s list or the MyDigitalLife forum post and you’ll have a pretty good idea of what media was used to install Windows. I’ll be on the look out for any official and up-to-date documentation on the Channel ID in the mean time.
Do you know of a better way? Have any insights on official documentation? Let me know in the comments below.