What does "404 (64)" mean?

Question

With Chrome's console open on ncoa.org, I saw the following two errors. Only the second of which is what I expect.

Failed to load resource: the server responded with a status of 404 (64)
Failed to load resource: the server responded with a status of 404 (Not Found)

What I am wondering is: where did the (64) come from?

Note that this isn't reliably reproducible. It only seems to happen sometimes, but I've seen it elsewhere and managed to grab a screenshot there. I'm hoping this is something more interesting than a reference to a 64-bit process sneaking in or whatever.

Here are the missing resources:
http://www09.clicktale.net/i/7798.gif?r=0.335&UID=1299415204.1646124943&441321531 http://www.ncoa.org/assets/img/highslide/loader.white.gif

Any ideas? :)

Answer 1

The "(64)" is returned by the web server in the 404 response for that request:

 % curl -v 'http://www09.clicktale.net/i/7798.gif?r=0.335&UID=798271705.1983171051&new&1053566178'
* About to connect() to www09.clicktale.net port 80 (#0)
*   Trying 75.125.82.68...
* Connected to www09.clicktale.net (75.125.82.68) port 80 (#0)
> GET /i/7798.gif?r=0.335&UID=798271705.1983171051&new&1053566178 HTTP/1.1
> User-Agent: curl/7.29.0
> Host: www09.clicktale.net
> Accept: */*
>
< HTTP/1.1 404 64
< Cache-Control: private
< Content-Type: text/html
< Date: Fri, 18 Apr 2014 19:01:05 GMT
< Content-Length: 1245
<
< !DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
...

Note the line that begins with HTTP. More usually this would end with some text like Not found but in this case the server administrator has set it up differently. You'd have to ask them what the significance of the "64" is.