If you get the following message when trying to download an .iso disc image from IIS 7/7.5…
404 – File or directory not found.
The resource you are looking for might have been removed, had its name changed, or is temporarily unavailable.
You just need to add the MIMI type. To do this, open IIS Manager, select the server on the left, open MIME Types…
Then on the top right click Add > File name extension: .iso
MIME Type: application/octet-stream
The file should now download properly.