Why can FortiGuard Servers not be blocked with a policy?

[fakecharle]

This post is tied to another one  (see link to post below) I made regarding using the ISP DNS servers for DNS resolution rather than FortiGuard DNS servers or having to specify the DNS ISP  servers IP addresses manually in the Fortigate DNS settings. To see if I could disable DNS resolution with FortiGuard DNS servers, I have tried to set in the Fortigate settings the primary DNS as 1.1.1.1 and the secondary dns server as 8.8.8.8 and then making a policy which blocks all communication for all services between my host and the FortiGuard DNS servers (i.e. 96.45.45.45 and 96.46.46.46). However, after doing all of this, if I run nslookup youtuber.com 96.45.45.45, my query is resolved. How is this possible? How may I disable all communication to the Fortiguard DNS servers?

Post link: https://community.fortinet.com/t5/Support-Forum/How-to-configure-a-LAN-interface-with-DHCP-disabled-...

[Shashwati]

hello, please refer to the following document

https://docs.fortinet.com/document/fortigate/6.2.16/cookbook/691614/override-fortiguard-servers