title: What does Apache Bench consider a failure?
body: <p>I have been using Apache Bench in work to benchmark a number of servers. After testing one of them I got this result:</p>
  
  <pre><code>Concurrency Level:      10
  Time taken for tests:   13.564 seconds
  Complete requests:      500
  Failed requests:        497
  (Connect: 0, Length: 497, Exceptions: 0)
  </code></pre>
  
  <p>There is no sign of an error in the server's log file. This makes me believe that it is Apache Bench that is treating successful requests as fails. With that in mind, can anyone explain to me what does Apache Bench considers a failed request?</p>