HTTP 301
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The HTTP response status code 301 Moved Permanently is used for permanent URL redirection, meaning current links or records using the URL that the response is received for should be updated. The new URL should be provided in the Location field included with the response. The 301 redirect is considered a best practice for upgrading users from HTTP to HTTPS.[1] RFC 2616 states that:
- If a client has link-editing capabilities, it should update all references to the Request URL.
- The response is cachable.[2]
- Unless the request method was HEAD, the entity should contain a small hypertext note with a hyperlink to the new URL(s).
- If the 301 status code is received in response to a request of any type other than GET or HEAD, the client must ask the user before redirecting.
Example
Client request:
GET /index.php HTTP/1.1 Host: www.example.org
Server response:
HTTP/1.1 301 Moved Permanently Location: http://www.example.org/index.asp
Here is an example using a .htaccess file to redirect a non-secure URL to a secure address without the leading "www":
RewriteEngine On RewriteCond %{HTTPS} off RewriteCond %{HTTP_HOST} ^www\.(.*)$ [NC] RewriteRule ^(.*)$ http://%1/$1 [R=301,L] RewriteCond %{HTTPS} on RewriteCond %{HTTP_HOST} ^www\.(.*)$ [NC] RewriteRule ^(.*)$ https://%1/$1 [R=301,L] RewriteEngine On RewriteCond %{SERVER_PORT} 80 RewriteRule ^(.*)$ https://example.com/$1 [R,L]
Here is an example using a PHP redirect:
<?php header("HTTP/1.1 301 Moved Permanently"); header("Location: http://example.com/newpage.html"); exit(); ?>
Equivalently simple for an nginx configuration:
location /old/url/ { return 301 /new/url; }
Search engines
Both Bing and Google recommend using a 301 redirect to change the URL of a page as it is shown in search engine results.[3][4]
See also
References
- ^ "Secure your site with HTTPS". support.google.com. Google. Retrieved 6 February 2016.
- ^ How long do browsers cache HTTP 301s? - https://stackoverflow.com/questions/9130422/how-long-do-browsers-cache-http-301s
- ^ Site Move Tool - Bing Webmaster Help & How-to - https://www.bing.com/webmaster/help/how-to-use-the-site-move-tool-bb8f5112
- ^ 301 redirects - Google Webmaster Tools Help - http://support.google.com/webmasters/bin/answer.py?hl=en&answer=93633