I'm going to block all bots except the big search engines.
One of my blocking methods will be to check for "language":
If it has no Accept-Language the bot's IP adress will be blocked untill 2037.
Googlebot do not have
Accept-Language, I want to verify it with DNS lookup
<?php gethostbyaddr($_SERVER['REMOTE_ADDR']); ?>
Is it ok to use
gethostbyaddr, can someone pass my "