A threat actor’s command-and-control infrastructure uses hard-coded IP addresses and several domains resolved through DNS.

Option D blocks both indicator types at the appropriate enforcement layers. Hard-coded IP callbacks can be matched through a destination IP group referenced by a Cloud Firewall Drop rule, while domain-based callbacks can be denied through a custom URL category and URL Filtering policy. Positioning the specific Firewall denial before generic outbound allows ensures that it is evaluated. Zscaler’s Destination IP Group documentation explains how IP addresses, FQDNs, and URL categories are grouped for Firewall policy. The URL Filtering overview documents rules based on URL categories, users, groups, and other criteria. Browser Isolation permits controlled rendering and is not the correct response for confirmed command-and-control infrastructure. TLS inspection alone does not constitute a deny decision. Risk-based page scoring is less deterministic than explicitly blocking known indicators and does not adequately address hard-coded IP callbacks.

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