F5 Cloud-Native Functions For Secure DNS
Nice one Terence_Kam !
In BIG-IP, there is the ability to have a "DNS Security" profile attached to a DNS profile on the Virtual Server. ref: https://my.f5.com/manage/s/article/K18522641 and https://techdocs.f5.com/en-us/bigip-15-1-0/big-ip-network-firewall-policies-and-implementations/afm-protocol-security/dns-protocol-security/about-dns-protocol-filtering/filtering-dns-traffic-with-a-dns-security-profile.html
I couldn't find a reference for it in the F5BigDnsCache reference documents - is this why you are using the IPS profile instead?
The reason for asking being typically in BIG-IP the protocol profile (like DNS) can have a lot of the protocol validation and security done as part of parsing the packet for further processing, and IPS are typically used for more "bump-in-the-wire" pass-through traffic BIG-IP (such as AFM in forwarding mode).