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Table Of Contents  The TCP/IP Guide
 9  TCP/IP Application Layer Protocols, Services and Applications (OSI Layers 5, 6 and 7)
      9  TCP/IP Key Applications and Application Protocols
           9  TCP/IP File and Message Transfer Applications and Protocols (FTP, TFTP, Electronic Mail, USENET, HTTP/WWW, Gopher)
                9  TCP/IP World Wide Web (WWW, "The Web") and the Hypertext Transfer Protocol (HTTP)
                     9  TCP/IP Hypertext Transfer Protocol (HTTP)
                          9  HTTP Message Headers

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HTTP General Headers
(Page 2 of 3)


Contains instructions that pertain only to this particular connection, and must not be retained by proxies and used for further connections. The most common use of this header is with the parameter “close”, as follows:

Connection: close

This overrides the default persistent connection behavior of HTTP/1.1, forcing the connection to terminate after the server's response. Connection is a hop-by-hop header.


Indicates the date and time when the message originated. This is the same as the Date header in the RFC 822 e-mail format. A typical example would be:

Date: Wed, 06 Aug 2003 16:43:50 GMT

Used to enable implementation-specific directives to be applied to all devices in the request/response chain. One common use of this header is to suppress caching by including “Pragma: no-cache” in a message. This has the same meaning as a “Cache-Control: no-cache” header, and is included in HTTP/1.1 for backward compatibility with HTTP/1.0 (which supports Pragma but not Cache-Control).


When “chunked” transfers are used, certain headers may be placed as trailers, after the data being sent. In this case, the Trailer header is included before the data, and lists the names of the headers that are actually trailers in that message. This warns the recipient to look for them after the data. Trailer is a hop-by-hop header.


Indicates what encoding has been used for the body of the message, to ensure that it is able to be transferred properly between devices. This header is most often used with the “chunked” transfer method. Note that this header describes encoding applied to an entire message, and is thus not the same as the Content-Encoding entity header, which specifically describes the entity carried in a message. See the topic on content and transfer encodings for a full discussion. This header applies only to a single transfer, so it is a hop-by-hop header.

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Version 3.0 - Version Date: September 20, 2005

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