AS203446 Smartnet SmartMitigate does not allow recursive DNS servers. Your server must use one of these DNS resolvers:
1.1.1.1(Cloudflare)1.0.0.1(Cloudflare)8.8.8.8(Google)8.8.4.4(Google)9.9.9.9(Quad9)2606:4700:4700::1111(Cloudflare)2606:4700:4700::1001(Cloudflare)2001:4860:4860::8888(Google)2001:4860:4860::8844(Google)
Queries sent to other DNS servers will not receive a response.