bind

For security reasons, it's recommended to disable recursive DNS lookups. Here is how:

Find out your named version

named -v

If your BIND version is at least 9.x then insert the following, between options { }:

        // Deny recursive lookups
        allow-query     { any; };
        allow-transfer  { none; };
        allow-recursion { localhost; };
        recursion yes;

So it looks like something like this: