An administrator configures FortiGuard servers as DNS servers on FortiGate using default settings.

“When using FortiGuard servers for DNS, FortiOS uses DNS over TLS (DoT) by default to secure the DNS traffic. New FortiGuard DNS servers have been added as primary and secondary servers.”

Technical Deep Dive:

The correct answer is C. It uses DNS over TLS .

This is a direct default-behavior question. If you configure FortiGuard servers as DNS servers and do not change anything else, FortiGate uses DoT rather than plain DNS. That means the DNS session is encrypted, which protects DNS queries from simple interception or tampering on the path.

Why the other options are wrong:

A is standard clear-text DNS behavior, not the FortiGuard DNS default stated in the guide.

B is incorrect because the guide specifically says DNS over TLS , not DNS over HTTPS.

D is incorrect; the guide does not describe UDP 8888 as the default transport for this DNS use case.

Operationally, this matters because FortiGate relies on DNS not only for client-facing services, but also for resolving objects and securely reaching cloud-based services. Using DoT improves confidentiality for those DNS lookups.