dstiles - 11:39 pm on Nov 8, 2011 (gmt 0)
Pfui - I hold the ranges in a MySQL database, wherein are all other blockable ranges, short-term auto-blocks etc. When I detect a bingbot UA I check it against the IP. If there is no match, no access. Which is why I'd run up a massive block list of 157 IPs until this list got added.
Reason for the method is historical as much as anything - my security system is a decade or more old, built when IIS had no proper regex let alone a decent htaccess capability.