title: 304 Not Modified When If-None-Match is valid
body: <p>I am optimizing an Express JSON API for consumption by iOS &amp; Android Apps and do not seem to be able to get Express to respond with the correct 304 header when the Apps specify an etag within the If-None-Match header.</p>
  
  <p>I needn't setup Etag generation as Express was already providing those; however when the Apps specify that etag again in a second request; Express' response is still a 200 with the data, as you can see in my tests in Postman: </p>
  
  <p><img src="https://i.stack.imgur.com/JEcXX.png" alt="Postman request with correct If-None-Match header and 200 response"></p>
  
  <p>How can I enable this functionality?</p>
  
  <p><strong>Update:</strong> The iOS dev is seeing the correct 304 Not Modified responses from the Express server but I don't understand why I am not seeing them within Postman - Does Postman support such actions?</p>