A recent study commissioned by Infoblox and performed by The Measurement Factory suggests that incorrectly configured DNS servers present a security problem waiting to happen. More than 50% of DNS servers that allow recursive name services that relay requests to other name servers are vulnerable. DNS servers running BIND 8, an older, less secure and less reliable version of DNS software in 2006: 15% of those running the older version of DNS software in 2005: 20% of the DNS software that was released in 2005.”]
Source: https://www.csoonline.com/article/2122005/-not-so–eminent-domains.html