The tool generate two lists, one for IPv4 (list4.json) and one for IPv6
(list6.json) to allow the user to only enable one of the two.
The list is downloaded from http://public-dns.info/ and a sample of the
list was tested with:
for dns in $( awk -F "," '{ print $1 }' < nameservers.csv ) ; do dig +noedns @$dns google.com | grep NOERROR 1>/dev/null || echo $dns ; done
~95% of the tested servers responded. So the list is not all crap.