See topic. This behaviour appears to be common across all sites. Tested on:
- stackoverflow.com
- serverfault.com
- superuser.com
- programmers.stackexchange.com
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?