Restarting FTP Uploads and Downloads (IIS 6.0)

If your connection closes unexpectedly while uploading or downloading a file using FTP, it might not be necessary to transfer the entire file again, because the IIS -based FTP service supports restarting failed FTP uploads and downloads. If your FTP client software supports FTP restart, you can reestablish the FTP connection and restart the file transfer; and the file transfer will automatically pick up where it left off.

The command-line FTP client included with Microsoft Windows does not support restarting downloads. You must use a third-party command-line FTP client for that functionality. If you are using a command-line FTP client, uploads can be resumed by using the append command to add data to an existing file. Downloads can be restarted by first issuing a rest command with the desired offset, and then issuing the retr command.


The IIS implementation of FTP restart is limited to an offset of less than four gigabytes.

For information on installing the FTP service, see FTP Site Setup.

For information on the commands supported by the Microsoft Windows command-line FTP client, search for "ftp" on the Microsoft Developer Network (MSDN) Web site.

For the official FTP specification with the entire FTP command set, see the World Wide Web Consortium Web site.

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