// get latest apt
deb http://cz.archive.ubuntu.com/ubuntu cosmic main universe
// install related tools
apt install knot-dnsutil ldnsutils
// cd into knot-resolver dir
cd /etc/knot-resolver
// download root.key
kdig DNSKEY . @k.root-servers.net +noall +answer | grep "DNSKEY[[:space:]]257" > root.keys
// edit kresd.conf
-- Enable DNSSEC validation
trust_anchors.file = '/etc/knot-resolver/root.keys'
Mac stubby client view log
sudo tail -f /usr/local/var/log/stubby/stubby.log