If you know its possible to issue Range requests against your server, it's vulnerable.
If you know for sure it's _not_ possible to issue such requests (e.g. they will definitely always result in an error) then it's not vulnerable.
If you're not sure, the former is far more likely than the latter, lots of things might allow Range requests, and it only takes one.
The "killapache.pl" script requires that the remote server is willing to compress data with gzip/ deflate. This is completely tangential to the actual problem, and so the script is largely useless as a "test tool".