title: what is the difference in resolver valid time and resolver_timeout in nginx
body: <p>I have this nginx configuration entry.</p>
  
  <pre><code>http {
    resolver 172.17.42.1 valid=600s;
    resolver_timeout 60s;
  </code></pre>
  
  <p>In this configuration there 2 two different timeouts. 
  The nginx <a href="http://nginx.org/en/docs/http/ngx_http_core_module.html#resolver" rel="noreferrer">documentation</a> does not make it clear to me what is the difference between <strong>valid</strong> and <strong>resolver_timeout</strong>.</p>
  
  <p>Can someone explain in detail?</p>