Large File Upload in IIS
By default, IIS web server allows for limited file size to be uploaded to the web server. For IIS 6 and IIS 7, the default maximum file upload size is 4 MB and 28.6 MB respectively. In order to allow for larger file size uploads, a few server changes are required.
In some situations, you may still cannot upload large files even you've modified the settings of your server as required. The following guidelines provide several techniques for debugging this issue.