I cant find that in the RFC2616, but it's a well known issue. A request on http://my-server/my/ressource asks for the ressource file and not a directory. Assuming that the ressource doesn't exist but is in fact a directory, some servers will then redirect the client to the right URL : http://my-server/my/ressource/ (note the final slash) Apache's mod_rewrite seems to correct that, but some other servers would not . As an exemple, try to ask for http://www.google.com/services , and watch the response from GWS. It responds a 303 code with a location to http://www.google.com/services/ (note the final slash). This wastes ressources, both for the server, and all the Internet links as 1 HTTP request in fact needs 2... Zend Framework's router does not generate final slashes on ressources, for exemple, try to use the url() view helper and you will notice that. This is mitigated by the fact that Apache's mod rewrite correct that, preventing a 30* response, but the problem is still present. For more information I suggest : http://developer.yahoo.net/blog/archives/2007/07/high_performanc_9.html http://httpd.apache.org/docs/2.0/mod/mod_dir.html