For ZDLRA the protection policies have a significant role in the appliance management, but not just that, for the architecture design too. And usually (and unfortunately) policies do not take a lot of attention as deserved.
To create a good ZDLRA design, and avoid future problems, it is important to understand all the requirements for the protection policies and all the impacts. You can check the official documentation for this, but I will explain deeply the details that can pass without you notice them in the documentation.