HTTP Header Detailed

HTTP (Hypertexttransferprotocol) is a universal protocol for Hypertext Transfer Protocol, which is currently transmitted on Web pages. The HTTP protocol uses the request/response model, where the browser or other client makes the request and the server responds. For the entire network resource transmission, including Message-header and message-body two parts. First pass the Message-header, i.e. HTTP HeaderNews . HTTP header messages are usually divided into 4 sections: general header, request header, response header, entity header. But this division is understood, the sense of the boundary is not very clear. Based on Wikipedia's organization of HTTP header content, it is broadly divided into two parts: request and response.

Header explanation Example

Accept-ranges	Indicates whether the server supports the specified range request and what kind of staging request	Accept-ranges:bytes
Age	Estimated time (in seconds, non-negative) from the original server to the proxy cache	Age:12
Allow	A valid request behavior for a network resource is not allowed to return 405	Allow:get, HEAD
Cache-control	Tell if all caching mechanisms can be cached and which type	Cache-control:no-cache
Content-encoding	The type of return content compression encoding supported by the Web server.	Content-encoding:gzip
Content-language	The language of the response body	Content-language:en,zh
Content-length	The length of the response body	content-length:348
Content-location	Alternate alternative address to request resource substitution	Content-location:/index.htm
Content-md5	Returns the MD5 checksum value of a resource	content-md5:q2hly2sgsw50zwdyaxr5iq==
Content-range	The byte position of this section in the entire return body	Content-range:bytes 21010-47021/47022
Content-type	Returns the MIME type of the content	content-type:text/html; Charset=utf-8
Date	Time the original server message was issued	Date:tue, 08:12:31 GMT
ETag	The current value of the entity label of the request variable	ETag: "737060cd8c284d8af7ad3082f209582d"
Expires	Date and time when the response expires	Expires:thu, 16:00:00 GMT
Last-modified	Requested last modified time for resource	Last-modified:tue, 12:45:26 GMT
Location	Used to redirect the receiver to the location of the non-request URL to complete the request or identify the new resource	Location:http://www.zcmhi.com/archives/94.html
Pragma	Includes implementing a specific instruction that can be applied to any receiver on the response chain	Pragma:no-cache
Proxy-authenticate	It indicates the authentication scheme and the parameters on the URL that can be applied to the proxy	Proxy-authenticate:basic
Refresh	Applied to redirect or a new resource was created, redirected after 5 seconds (proposed by Netscape, supported by most browsers)	Refresh:5; Url=http://www.zcmhi.com/archives/94.html
Retry-after	Notifies the client to try again after a specified time if the entity is temporarily undesirable	retry-after:120
Server	Web Server Software Name	server:apache/1.3.27 (Unix) (Red-hat/linux)
Set-cookie	Set HTTP Cookies	Set-cookie:userid=johndoe; max-age=3600; Version=1
Trailer	Indicates that the header domain is present at the end of the chunked transfer code	Trailer:max-forwards
Transfer-encoding	File transfer encoding	Transfer-encoding:chunked
Vary	Tells the downstream agent whether to use the cache response or request from the original server	Vary: *
Via	Tells the proxy client where the response was sent by	via:1.0 Fred, 1.1 nowhere.com (apache/1.1)
Warning	Warning about possible issues with the entity	warning:199 Miscellaneous Warning
Www-authenticate	Indicates the authorization scheme that the client request entity should use	Www-authenticate:basic

See Website header Field Definitions

Content-type	The requested MIME information corresponding to the entity	content-type:application/x-www-form-urlencoded
Date	Date and time the request was sent	Date:tue, 08:12:31 GMT
Expect	The specific server behavior of the request	Expect:100-continue
From	Email from the user who made the request	From: [Email protected]
Host	Specify the domain name and port number of the requested server	Host:www.zcmhi.com
If-match	Only valid if the request content matches the entity	If-match: "737060cd8c284d8af7ad3082f209582d"
If-modified-since	If the requested part is modified after the specified time, the request succeeds, and the 304 code is returned without modification	If-modified-since:sat, Oct 19:43:31 GMT
If-none-match	If the content does not change the return 304 code, the parameter is the server's previously sent ETag, and the server responded to the ETag comparison to determine whether the change	If-none-match: "737060cd8c284d8af7ad3082f209582d"
If-range	If the entity does not change, the server sends the missing portion of the client, otherwise the entire entity is sent. The parameters are also ETag	If-range: "737060cd8c284d8af7ad3082f209582d"
If-unmodified-since	Request succeeds only if the entity has not been modified since the specified time	If-unmodified-since:sat, Oct 19:43:31 GMT
Max-forwards	Limit the time that information is transmitted through agents and gateways	Max-forwards:10
Pragma	Used to include implementation-specific instructions	Pragma:no-cache
Proxy-authorization	Connect to an authorization certificate for the agent	Proxy-authorization:basic qwxhzgrpbjpvcgvuihnlc2ftzq==
Range	Request only part of an entity, specify a range	range:bytes=500-999
Referer	The address of the previous page, which is immediately followed by the current request page,	Referer:http://www.zcmhi.com/archives/71.html
TE	The client is willing to accept the transfer encoding and notifies the server to accept the trailing header information	te:trailers,deflate;q=0.5
Upgrade	Specify some kind of transport protocol to the server for the server to convert (if supported)	upgrade:http/2.0, shttp/1.3, irc/6.9, rta/x11
User-agent	The content of the user-agent contains the user information that made the request	user-agent:mozilla/5.0 (Linux; X11)
Via	Notifies the intermediary gateway or proxy server address, communication protocol	via:1.0 Fred, 1.1 nowhere.com (apache/1.1)
Warning	About warning messages for message entities	warn:199 Miscellaneous Warning

Requests Partial Header explanation example

Accept	Specify what types of content clients can receive	Accept:text/plain, text/html
Accept-charset	The set of character encodings that the browser can accept.	Accept-charset:iso-8859-5
Accept-encoding	Specifies that the Web server that the browser can support returns the content compression encoding type.	Accept-encoding:compress, gzip
Accept-language	Browser-acceptable language	Accept-language:en,zh
Accept-ranges	You can request one or more child range fields for a Web page entity	Accept-ranges:bytes
Authorization	Authorization Certificate for HTTP Authorization	Authorization:basic qwxhzgrpbjpvcgvuihnlc2ftzq==
Cache-control	Specify the caching mechanism that requests and responses follow	Cache-control:no-cache
Connection	Indicates whether a persistent connection is required. (HTTP 1.1 defaults to persistent connection)	Connection:close
Cookies	When an HTTP request is sent, all cookie values stored under that request domain are sent to the Web server.	Cookie: $Version = 1; Skin=new;
Content-length	The requested content length	content-length:348

HTTP Header Detailed