title: HSTS should be minimum 180 days, why?
body: <p>I did a test of my site at ssllabs.
  I enabled HSTS for 90 days because I don't know how long I'll use SSL, and my current certificate ends in 89 days.</p>
  
  <p>Now I got the warning:</p>
  
  <blockquote>
    <p>TOO SHORT (less than 180 days)  max-age=7776000</p>
  </blockquote>
  
  <p>And that leaves me wondering, why the minimum of 180 days. Whats the reasoning behind a long HSTS?</p>