To quote the headline
NEW SURVEY REVEALS MORE THAN 75 PERCENT OF AUTHORITATIVE NAME SERVERS HAVE AN INCREASED VULNERABILITY TO DNS PHARMING ATTACKS
and the article itself
The most surprising result of the survey showed that between 75 and 84 percent of the name servers investigated provide recursive name services to arbitrary queriers on the Internet. Industry best practices dictate that recursive name services - a form of name resolution that may require a name server to relay requests to other name servers - should only be enabled on a DNS server for a restricted list of known, trusted requestors.
http://www.measurement-factory.com/press/20051024.html
http://dns.measurement-factory.com/surveys/sum1.html