root-hints
Instead of forwarding queries to a public DNS server, you may prefer to query the root DNS servers. To do this, comment out the forwarding entries ("forward-zone" sections) in the config. Then, grab the latest root hints file using wget:
wget -S -N https://www.internic.net/domain/named.cache -O /etc/unbound/root.hints
And finally point unbound to the root hints file by adding the following line to the server section of the unbound config file:
root-hints: "/etc/unbound/root.hints"
Restart unbound to ensure the changes take effect. You may wish to setup a cron job to update the root hints file occasionally.