I had a hell of a time wondering what was going wrong with my webserver under load and finally found the answer here.

Turns out that Apache Bench takes the first pulled request and compares the length to all subsequent requests. Makes sense for a purely static page, but when you have a random image cropping up, you’re sure to see at least a couple bits difference in length.

So if you’re serving straight, hand coded HTML, enjoy the feeling of knowing that you’re getting the same length content each and every time… but if you’re like the rest of us (and anyone who would actually be using Apache Bench) feel free to rage that there’s no command line switch to turn off that silly notification.