I have a client that wants to make their products firmware files available for download on their website. The firmware files have a custom extension: .bi2. The client wants the files to be downloaded directly and not placed in a container (like a .zip file).

Is there an IIS setting that will instruct the browser to download the .bi2 file instead of trying to open it as a webpage?

Thanks in advance for your help!

1 Answer 1


In order for IIS to allow access to the file at all, it needs to be assigned a MIME-type. Use application/octet-stream and the browser will almost certainly treat it as a file it can't handle itself.

(You could also experiment with application/x-whatever-you-want)

  • +1 It might be useful to edit your question to add instructions on how to define a MIME type for a specific extension under IIS. (i.e. Quote the step-by-step instructions from this page.)
    – Nick
    Commented Aug 19, 2011 at 12:38
  • @Nick, fair point, but first OP needs to edit the question to say which version of IIS, doesn't he? Commented Aug 19, 2011 at 12:59
  • @PeterTaylor, Great point, I posted both because I don't know the answer. This particular website is hosted off-site and I don't know a whole lot about it. You're answer was great, and sufficient. I really just need to sound intelligent when I contact the hosting provider.
    – James Hill
    Commented Aug 19, 2011 at 13:03

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