Option A places the threat-intelligence denial where it can match before generic outbound allows without unnecessarily rewriting Zscaler-managed Microsoft 365 logic. The subscribed addresses should be represented by an appropriate destination IP group and referenced in a specific Drop rule. Zscaler’s Destination IP Groups documentation confirms that destination addresses and categories can be grouped for Firewall policy enforcement. Its predefined Firewall Filtering rule documentation explains the special ordering of predefined rules, while Firewall Control best practices emphasize narrowly conditioned rules. Placing the block beneath broad allows makes it ineffective because first-match evaluation has already permitted the traffic. Editing predefined Microsoft 365 behavior introduces avoidable maintenance risk. Broad SaaS allows above the threat block also create the exact exposure the SOC is trying to eliminate.

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