When you use DNS on your operating systems and web browsers, you can encrypt the DNS
traffic to help maintain privacy and protect traffic from meddler (MitM) attacks. If
you configure your PAN-OS firewall to act as a DNS proxy, you can
enable encrypted DNS and configure the DNS
proxy to accept one or more types of DNS communication from the client:
DNS-over-HTTP (DoH), DNS-over-TLS (DoT), or cleartext.
To enforce encryption, you specify the type of encryption that the DNS proxy should
use to communicate with DNS servers. If a DNS server rejects encrypted DNS or the
DNS proxy does not receive a response from the primary or secondary server within
the timeout period, you can configure the DNS proxy to fall back to unencrypted DNS
communications with the server.