See all of the guides.

Setting up Caching-only DNS.

On the Server

yum install -y unbound

systemctl enable unbound; systemctl start unbound

vim /etc/unbound/unbound.conf

Minimal updates

interface: 0.0.0.0
access-control: 192.168.4.0/24 allow
forward-zone:
name: "."
  forward-addr: 192.168.4.200
  domain-insecure: example.com

Check the configuration

unbound-checkconf

Restart service

systemctl restart unbound

Open the firewall

firewall-cmd --permanent --add-service=dns

firewall-cmd --reload

Test by changing the name server to the unbound host ip in /etc/resolv.conf