See topic. This behaviour appears to be common across all sites. Tested on:
Curl output (with headers only) below.
Test 1 - with trailing dot:
% curl -I www.stackoverflow.com. HTTP/1.1 400 Bad Request Content-Length: 334 Content-Type: text/html; charset=us-ascii Date: Sat, 18 Dec 2010 21:06:17 GMT % curl -I stackoverflow.com. HTTP/1.1 400 Bad Request Content-Length: 334 Content-Type: text/html; charset=us-ascii Date: Sat, 18 Dec 2010 21:08:34 GMT
Test 2 - without trailing dot:
% curl -I www.stackoverflow.com HTTP/1.1 301 Moved Permanently Content-Length: 148 Content-Type: text/html; charset=UTF-8 Location: http://stackoverflow.com/ Date: Sat, 18 Dec 2010 21:07:48 GMT % curl -I stackoverflow.com HTTP/1.1 200 OK Cache-Control: public, max-age=60 Content-Length: 195426 Content-Type: text/html; charset=utf-8 Expires: Sat, 18 Dec 2010 21:08:54 GMT Last-Modified: Sat, 18 Dec 2010 21:07:54 GMT Vary: * Date: Sat, 18 Dec 2010 21:07:53 GMT
Update: The fact that many applications add the trailing dot implicitly doesn't remove the fact that a domain name isn't considered fully qualified unless the trailing dot is present. See the wiki page and RFC1535 as to why this matters.
In any case; a URL with a trailing dot on the FQDN is a well formed request. Is there any reason you believe it shouldn't be supported?