Firewall does WildFire Registration even though WildFire is Not Configured on the Firewall
To opt-out from this feature or to avoid WildFire public cloud registration, the user must disable passive DNS monitoring in the Anti-Spyware profile.
Please follow the steps below to disable Passive DNS monitoring,
Goto Object >> Security Profile >> Anti-Spyware >> select appropriate Anti-Spyware Profile >> Uncheck "Enable Passive DNS Monitoring".
Entering configuration mode
# set profiles spyware "Anti-Spyware profile name" botnet-domains passive-dns no