when enabling chassis clustering on two devices, the correct order for rebooting them is to reboot the primary device first, followed by the secondary device. It is not possible for either device to assign itself the correct cluster and node ID, so both devices must be rebooted to ensure the proper configuration is applied.

https://www.juniper.net/documentation/en_US/junos/topics/topic-map/security-chassis-cluster- dual-control-links.html

unified security policies are security policies that enable you to use dynamic applications as match conditions along with existing 5-tuple or 6-tuple matching conditions12. They simplify application-based security policy management at Layer 7 and provide greater control and extensibility to manage dynamic applications traffic3