If try to download he exe or dll file from the IIS server, you will get 404 file error. But this is incorrect settings in the IIS.
Why:
IIS Manager >> Website/VD >> Properties >> Home Directory >> Application Settings
Execute permissions set to "Scripts and Executables" in IIS.
Resolution:
IIS Manager >> Website/VD >> Properties >> Home Directory >> Application Settings
Set Execute permissions to "Scripts only" in IIS.
