August 1, 2010

Error Code 404- Page Not Found- A Brief Overview

The 404 or Not Found error message is a HTTP standard response code indicating that the client was able to communicate with the server but the server could not find what was requested. 404 errors should not be confused with "server not found" or similar errors, in which a connection to the destination server could not be made at all. Another similar error is "410: Gone", which indicates that the requested resource has been intentionally removed and will not be available again. A 404 error indicates that the requested resource may be available in the future.

When communicating via HTTP, a server is required to respond to a request, such as a web browser's request for an HTML document (web page), with a numeric response code and an optional, mandatory, or disallowed (based upon the status code) message. In the code 404, the first "4" indicates a client error, such as a mistyped URL. The following two digits indicate the specific error encountered. HTTP's use of three-digit codes is similar to the use of such codes in earlier protocols such as FTP and NNTP.

At the HTTP level, a 404 response code is followed by a human-readable "reason phrase". The HTTP specification suggests the phrase "Not Found" and many web servers by default issue an HTML page that includes both the 404 code and the "Not Found" phrase.

A 404 error is often returned when pages have been moved or deleted. In the first case, a better response is to return a 301 Moved Permanently response, which can be configured in most server configuration files, or through URL rewriting; in the second case, a 410 Gone should be returned. Because these two options require special server configuration, most websites do not make use of them.



404 errors should not be confused with DNS errors, which appear when the given URL refers to a server name that does not exist. A 404 error indicates that the server itself was found, but that the server does not have the requested page.

Some websites report a "not found" error by returning a standard web page with a "200 OK" response code; this is called a soft 404. Soft 404s are problematic for automated methods of discovering whether a link is broken. Soft 404s can occur as a result of configuration errors when using certain http server software, for example with the Apache software, when an Error Document 404 (specified in a .htaccess file) is specified as an absolute path (e.g. www.wikipedia.org/error.php) rather than a relative path (/error.php).


Enhanced by Zemanta

About the Author

Tomboy

Author & Editor

Has laoreet percipitur ad. Vide interesset in mei, no his legimus verterem. Et nostrum imperdiet appellantur usu, mnesarchum referrentur id vim.

Post a Comment

 
Iwebslog Blog © 2015 - Designed by Templateism.com