FtpWebResponse.LastModified Property

public static bool GetDateTimestampOnServer (Uri serverUri)
{
    // The serverUri should start with the ftp:// scheme.
    if (serverUri.Scheme != Uri.UriSchemeFtp)
    {
        return false;
    }

    // Get the object used to communicate with the server.
    FtpWebRequest request = (FtpWebRequest)WebRequest.Create (serverUri);
    request.Method = WebRequestMethods.Ftp.GetDateTimestamp;
    FtpWebResponse response = (FtpWebResponse)request.GetResponse ();
    Console.WriteLine ("{0} {1}",serverUri,response.LastModified);

    // The output from this method will vary depending on the 
    // file specified and your regional settings. It is similar to:
    // ftp://contoso.com/Data.txt 4/15/2003 10:46:02 AM
    return true;
}