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Many webmaster in the process of doing site diagnostics, often will see the site has not done 404 pages, the general method of judging is very simple, that is, in the search engine address bar casually enter a wrong link to the domain name, and then see if there are 404 pages. Is that right? 404 page exists meaning is to tell the browser and search engine requested the page does not exist or link wrong, you this check can only show that users see is 404 pages, but for search engine? will return the 404 status code for this page?
First come to look at the following two pictures, the 404 pages in Your eyes may not return 404 status code.
Harm
You can see the site, although it returns 404 pages to the user, but for the search engine is a normal page, which is often due to the wrong server-side configuration and lead to return to the "200" status code, although the access to the user, the HTTP status code is "404" or "200" and no difference, The same is improved user experience, but for search engines, this is very important, even fatal.
When a search engine spider asks for a "404" state response to an error URL address, that means that the URL address is invalidated, the page is no longer indexed, and the Web page represented by that URL address is deleted from the index database to the datacenter, and when the search engine gets a "200" for this 404 page State response, the URL address is considered valid. Will go to the index, and will be included in the index database, so that all of your error pages for search engines are different URL address content of the same page, which will lead to a large number of duplicate pages, will greatly reduce the quality of the site score, or even directly down the right.
So the properly set custom 404 error page should not only be able to be displayed correctly, but should also return "404" error codes instead of 200 or more. Not only to tell the user that the page does not exist, but also to correctly let the search engine know that this is a 404 error page rather than a normal page.
404 How the page is set correctly
1, ISS 404 error Page Setup
Open IIS Manager--> Click the properties of the Web site you want to set custom 404--> click Custom error option--> select 404 Page--> Select and open Edit Properties--> set to file or default value-->url fill in "/404.html , press OK to exit. Then upload a good 404.html page to the site root directory. In message type here, be sure to select file or default, rather than URL, which will result in the return of a "200" status code.
2, Apache set 404 error page is very simple, generally there is a 404 error page set up the function, you need to do a 404 page, upload the corresponding directory on it.
3, some host space default is to return the value of 320 or 200 status code, how to do? We can solve this by using the following code:
Set 404 error page under Apache server
Create a. htaccess file in which to add the following: ErrorDocument 404/ notfound.php, then upload the. htaccess file to the site root directory, and finally make a 404 page, named notfound.php, and the name above must be unified, the same upload to the site root directory OK. Here, remember not to use absolute URLs, if the status code returned using an absolute URL is 302 or 200.
Iis/asp.net Set 404 Error page
First, modify the settings for the application root directory, open the Web.config file, and reference the following:
Error.asp is the default 404 page name for the system, notfound.asp is a custom 404 page, please modify the file name when you use it.
Then, add the following code to the custom 404 page notfound.asp To ensure that the IIS server returns the 404 status code correctly. <% Response.Status = 404 Not found%><% Response.Status = 404 Not Found%>
All in all, the site's 404 pages must be set up, if said to return the 200 status code that is asking for trouble, rather than do. Wood-Wood SEO recommendations 404 Page Setup is complete, must check whether the correct, return must be 404 state, if your site because of more than 200 yards 404 pages and led to the right to drop, it is very tragic. In addition, we should pay attention to the appearance and experience of the page when making 404 pages, as far as possible not to automatically jump also don't just show this page can not access, 404 pages also need to have clear navigation, let users decide where to go, so as to retain users.
Author: wood-wood seo article address: Http://blog.sina.com.cn/mumuhouzi