How to return "HTTP 404/Page Not Found" for non-existing pages in Dokuwiki
DokuWiki by default returns 200 HTTP status code for non-existing pages. This might trigger duplicate content alert to search engines and would somehow affect the site's SEO. There's an option to still give the nice DokuWiki Not found page yet still returning the 200 HTTP code.
Steps
Access the Configuration Manager page
Use the following URL if the link is not available in your template.
http://www.yourwiki.com/doku.php?do=admin&page=config
You will need to log in if you're not already are.
Enable the Send "HTTP 404/Page Not Found" for non existing pages option
Find the option in the Advanced Settings→Send404 section.
Tick the check box to enable the option.