Use headers like Cache-Control: no-store to ensure the file isn't served from the user's browser cache or a CDN, which would give fake high speeds .
Using a large file, like a 10GB file, for your download speed test provides a more accurate representation of your internet connection's capabilities. Smaller files may not fully utilize your bandwidth, leading to inaccurate readings. A 10GB file, on the other hand, ensures that your internet connection is fully engaged, providing a more reliable measurement of your download speeds.
: Keep an eye on the download progress. You can usually do this by checking the download speed in real-time through your browser's download manager or the software you're using to download the file.