What does X-Backside-Transport Header do?
<p>I have come across this header for the first time and not sure what it does or mean. I have searched around and couldn't find what I was looking for.</p>

<p>I am trying to consume a SOAP API using PHP SoapClient class and it's returning an empty response and these response headers. Also, no exception is thrown.</p>

<pre><code>HTTP/1.1 200 OK
X-Backside-Transport: FAIL FAIL,FAIL FAIL
Connection: close
Transfer-Encoding: chunked
Content-Type: text/xml
Date: Tue, 21 Jun 2016 20:09:50 GMT
X-Client-IP: xx.xxx.xxx.xxx
</code></pre>

<p>Any help is appreciated.</p>