DuckDuckGo Headers - Firefox

Client:
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GET / HTTP/1.1
Host: duckduckgo.com
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:50.0) Gecko/20100101 Firefox/50.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate, br
Cookie: ak=-1; ae=t; 5=1
DNT: 1
Connection: keep-alive
Upgrade-Insecure-Requests: 1
If-None-Match: W/"588845f0-13bd"

Server Response:
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HTTP/2.0 304 Not Modified
Server: nginx
Date: Wed, 25 Jan 2017 06:36:00 GMT
Etag: "588845f0-13bd"
Expires: Wed, 25 Jan 2017 06:35:59 GMT
Cache-Control: no-cache
Strict-Transport-Security: max-age=31536000
X-Firefox-Spdy: h2