Refer to the exhibit. An engineer is modifying an access control pokey to add a rule to inspect all DNS traffic that passes through the firewall. After making the change and deploying the pokey they…

While security zones can be specified, the lack of zone definition does not prevent Snort inspection if traffic matches the rule; the issue is the rule's action.

If the rule intends to inspect 'all DNS traffic,' it implies that the port (53) and potentially broad source/destination networks are already defined, making the action the critical factor for inspection.

In Cisco Firepower Threat Defense (FTD), an access control rule with an action of 'Trust' explicitly bypasses all deeper inspection, including Snort intrusion detection. To ensure Snort inspection occurs, the rule's action must be configured as 'Allow' (or 'Monitor' for passive detection) and an intrusion policy must be applied to that rule.

If the rule was configured with the wrong source port, the DNS traffic would not match the rule at all, rather than matching and then not being inspected by Snort.