RFC 2616
10.4.5 404 Not Found
The server has not found anything matching the Request-URI. No
indication is given of whether the condition is temporary or
permanent. The 410 (Gone) status code SHOULD be used if the server
knows, through some internally configurable mechanism, that an old
resource is permanently unavailable and has no forwarding address.
This status code is commonly used when the server does not wish to
reveal exactly why the request has been refused, or when no other
response is applicable.
Dib: A Colony of horrible Rat People! Hey, do you know the way outta here? Rat Man: There is no way out, we all got lost here too! And we've been here ever since!