404 the impact of error handling on SEO
Http status code:
404: the server cannot find the specified resource, the requested page does not exist (such as web browser requests to be deleted or displaced, but does not rule out the possibility of days after the effective link);
410: the requested page does not exist (Note: 410 indicates a permanent, and the represents a temporary);
200: the server successfully returns the requested page;
301: URL permanent redirection
302: URL temporary redirect
note: most search engines will be "404" and "" status equal treatment, such as Google. (see Matt Cutts for instructions)
understanding of HTTP404 state codes
HTTP 404 error means that the link to the page does not exist, namely the original "URL failure, this situation often happens, it is difficult to avoid, for example:" URL "generation rules change, file rename or move the location, link spelling error, lead to the original address URL cannot be accessed when the Web server; received a similar request, will return a 404 status code that tells the browser to request the resource does not exist. However, the 404 error page Web server by default, regardless of Apache or IIS, are very simple, inflexible and not friendly to the user, unable to provide the necessary information to get more clues, this will undoubtedly result in the loss of users.
so many sites use custom 404 error to provide user experience to avoid the loss of users. Generally speaking, a custom 404 page general practice is to put on the website, fast navigation links in the page search box and special service website, which can effectively help users access the site and get the information you need.
custom 404 error page is to provide the user experience good practice, but in the application process often did not pay attention to the impact on the search engine such as: the wrong server configuration to return "200" status code or a custom 404 error page using the Meta Refresh to return to "302" status code. Correctly set the custom 404 error page, should not only be able to correctly display, at the same time, should return the "error" of the "404"