Oh Good Grief!
404
Page not found
Whatever you was lookin' for, it ain't here.
Perhaps a search or one of the links below can help.
*Now, if you need to satiate your curiousity about the 404 message in general, you might course visit the 404 Page Museum. And if you're unshakably convinced that your packet just ended up in the bit-bucket somewhere, you can always look for it in the lost and found bin for misguided TCP packets. But good luck with that.