Please Whitelist This Site?

I know everyone hates ads. But please understand that I am providing premium content for free that takes hundreds of hours of time to research and write. I don't want to go to a pay-only model like some sites, but when more and more people block ads, I end up working for free. And I have a family to support, just like you. :)

If you like The TCP/IP Guide, please consider the download version. It's priced very economically and you can read all of it in a convenient format without ads.

If you want to use this site for free, I'd be grateful if you could add the site to the whitelist for Adblock. To do so, just open the Adblock menu and select "Disable on tcpipguide.com". Or go to the Tools menu and select "Adblock Plus Preferences...". Then click "Add Filter..." at the bottom, and add this string: "@@||tcpipguide.com^$document". Then just click OK.

Thanks for your understanding!

Sincerely, Charles Kozierok
Author and Publisher, The TCP/IP Guide


NOTE: Using software to mass-download the site degrades the server and is prohibited.
If you want to read The TCP/IP Guide offline, please consider licensing it. Thank you.

The Book is Here... and Now On Sale!

Get The TCP/IP Guide for your own computer.
The TCP/IP Guide

Custom Search







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

Previous Topic/Section
HTTP Request Headers
Previous Page
Pages in Current Topic/Section
1
2
Next Page
HTTP Entity Headers
Next Topic/Section

HTTP Response Headers
(Page 2 of 2)

Proxy-Authenticate

This is the proxy version of the WWW-Authenticate header (see below). It is included in a 407 (“Proxy Authentication Required”) response, to indicate how the proxy is requiring the client to perform authentication. The header specifies an authentication method as well as any other parameters needed for authentication. The client will use this to generate a new request containing a Proxy-Authorization header. This is a hop-by-hop header.

Retry-After

This header is sometimes included in unsuccessful requests—such as those resulting in a 503 (“Service Unavailable”) response—to tell the client when it should try its request again. It may also be used with a redirection response such as 301, 302 or 307, to indicate how long the client should wait before sending a request for the redirected URL. The Retry-After header may specify either a time interval to wait (in seconds) or a full date/time when the server suggests the client try again.

Server

This is the server's version of the User-Agent request header; it identifies the type and version of the server software generating the response. Note that proxies do not modify this field when forwarding a response; they put their identification information into a Via header instead.

Vary

Specifies which request header fields fully determine whether a cache is allowed to use this response to reply to subsequent requests for the same resource without revalidation. A caching device inspects the Vary header to determine which other headers it needs to examine to determine whether or not it can respond with a cached entry, when the client makes its next request for the resource in this reply. Yeah, this one's a bit confusing.

WWW-Authenticate

This header is included in a 401 (“Unauthorized”) response, to indicate how the server wants the client to authenticate. The header specifies an authentication method as well as any other parameters needed for authentication. The client will use this to generate a new request containing an Authorization header.

Key Concept: HTTP response headers appear in HTTP Response messages, where they provide additional information about HTTP server capabilities and requirements, and the results of processing a client request.



Previous Topic/Section
HTTP Request Headers
Previous Page
Pages in Current Topic/Section
1
2
Next Page
HTTP Entity Headers
Next Topic/Section

If you find The TCP/IP Guide useful, please consider making a small Paypal donation to help the site, using one of the buttons below. You can also donate a custom amount using the far right button (not less than $1 please, or PayPal gets most/all of your money!) In lieu of a larger donation, you may wish to consider purchasing a download license of The TCP/IP Guide. Thanks for your support!
Donate $2
Donate $5
Donate $10
Donate $20
Donate $30
Donate: $



Home - Table Of Contents - Contact Us

The TCP/IP Guide (http://www.TCPIPGuide.com)
Version 3.0 - Version Date: September 20, 2005

© Copyright 2001-2005 Charles M. Kozierok. All Rights Reserved.
Not responsible for any loss resulting from the use of this site.