That is a dummy IP.

Now, seeing is believing -- I gave it another try and it actually gave me the response similar to the screenshot.
Not sure why but it is very sporadic. I believe that, if cache file doesn't exist response is still 404.
Of course, the cache file exists, therefore question is - why so sporadic.
Wouldn't be helpful to return a message "cache file does not exists" instead of a 404.

Thanks again.