When I try to enter anything nonexistent after my blog's URL (kefzona.com) - it gives the 404 page.
BUT when I use Cyrillic characters (eg: http://kefzona.com/дад) I almost always get the post listing for the default category ("Друго", with slug "drugo"). The only exception is if I enter an actual category name from my blog (eg: "музика", which is an existing category in the blog), in which case I get the posts listed for the corresponding category (eg: the posts filled under "музика").