why between nginx/nginx upstream use http/1.0?
<p>I have 3 server:
A(nginx)-->B(nginx)-->C(nodejs),</p>

<p>When i access A or B,chrome use http/1.1+keepalive by default.</p>

<p>I do not set "proxy_http_version 1.1;" and  proxy_set_header Connection "";</p>

<p>But between A and B,NGINX use http/1.0 by default。That is like:</p>

<p><strong>client</strong> --> <strong>nginxA(upstream to b)</strong> --> <strong>nginxB(upstream to c)</strong> --><strong>C (nodejs)</strong>  </p>

<p><strong>http/1.1</strong> --> <strong>http/1.0</strong> --> <strong>http/1.1</strong> --> <strong>nodejs</strong></p>

<p>My questions is :
why nginx use http/1.1 for upstream by default，between nginx and nginx, upstream use http/1.0 ?</p>

<p>THX.</p>