Response header
A response header is an HTTP header that can be used in an HTTP response and that doesn't relate to the content of the message. Response headers, like Age
, Location
or Server
are used to give a more detailed context of the response.
Not all headers appearing in a response are categorized as response headers by the specification. For example, the Content-Length
header is an Representation metadata header indicating the size of the body of the response message (and as an entity header in older versions of the specification). However, "conversationally" all headers are usually referred to as response headers in a response message.
The following shows a few response headers after a GET
request. Note that strictly speaking, the Content-Encoding
and Content-Type
headers are entity header:
200 OK
Access-Control-Allow-Origin: *
Connection: Keep-Alive
Content-Encoding: gzip
Content-Type: text/html; charset=utf-8
Date: Mon, 18 Jul 2016 16:06:00 GMT
Etag: "c561c68d0ba92bbeb8b0f612a9199f722e3a621a"
Keep-Alive: timeout=5, max=997
Last-Modified: Mon, 18 Jul 2016 02:36:04 GMT
Server: Apache
Set-Cookie: mykey=myvalue; expires=Mon, 17-Jul-2017 16:06:00 GMT; Max-Age=31449600; Path=/; secure
Transfer-Encoding: chunked
Vary: Cookie, Accept-Encoding
X-Backend-Server: developer2.webapp.scl3.mozilla.com
X-Cache-Info: not cacheable; meta data too large
X-kuma-revision: 1085259
x-frame-options: DENY