Redirection Impact

Technical background
Due to the users' behaviour such as 'guessing url', wrong references, mistyping on an other web page, modifying structure of the web site, etc., users may request non-existing (wrong) URLs. The difference between the good/existing and wrong/non existing urls is based on the HTTP Status Code:


 * The existing page returns 2xx code (mostly 201). This means all is OK and for example the internet browsers displays simply a web page requested.
 * A non existing page returns 4xx code (well know pages Error 404 or Error 500)..

Typically the Flexible Redirection (very much used in the Commission for customising the 4xx Error Page) is based on capturing requests with 4xx code and replacing them with predefined response (prepared web page) and then responding with 201 code.

Wrong Number of Pages View
The Europa Analytics uses the web log analysis to produce the indicators. Any request (hit ) is registered to the log together with HTTP Status Codes.

If there is used (flexible) redirection which modifies the HTTP Status Code from 3xx and 4xx to 2xx, then "wrong" requests are considered as hitting a real content and so not correctly aggregated within the Server Errors, but as Page Views (but this can affect also Visits)

An example of such behaviour is the report on 'languages for Barroso (Commission 2010-2014) for March 2010', where the ES is far more popular then PT, while the site does not exist in ES.

Many Visits but 'zero' Page Views
This is an extreme case for a whole website, but rather common when analysing a subsite or specific url due to heavily used redirections.

As previously described, a request with HTTP Status Code different than 2xx is not counted as page view (no real content delivered). Nevertheless, being a tentative to access the website it has to be counted as a visit.

The number of the visits higher then number of pages view (extreme case: many visit with zero page views) shows excessive use of redirections; which is (in the most cases) creating negative User Experience and creating also other "problems". Webmasters should therfore detect and reduce redirections in order to limit this situation.

Impacts to Content of website

 * Tools tracking broken hyper-links
 * Tracking broken links is based on the HTTP Status Code. When the url with the Flexible Redirection is used it will be not listed (and so never corrected by a webmaster).


 * Search Engines
 * Error Pages and Redirection Pages are never indexed. But if a website is restructured then with the next updating of the index, all pages with response different to 2xx HTTP Status Code are removed. Most of Search Engines implements correctly the 301 (moved permanently) and if the new url is mentioned it is directly updated.
 * When Search Engines keep receiving the 2xx codes (due to for example Flexible Redirection) no changes are applied and visitors are redirected to the error page before moving towards real content. (Problem particularly experienced after migration from .eu.int to .eu, when websites kept referring to old urls).