NSE4 Firewall Policies and NAT Practice Question
Which of the following statements about FortiGate policy lookup order is correct?
⚠ Common exam trap
Test-takers frequently confuse FortiGate's sequential top-down evaluation with other firewall platforms (like Cisco ASA) that use a priority-based or implicit-rule model, leading them to incorrectly select Option B or C.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Policies are evaluated from top to bottom, and the first matching policy is used
FortiGate uses a top-down sequential search for policy matching. When a packet arrives, the firewall starts at the top of the policy list and evaluates each policy in order until it finds one where all configured criteria (source, destination, service, schedule, etc.) match. The first matching policy is then applied, and no further policies are checked. This is the fundamental behavior of FortiGate's firewall policy lookup.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Policies are evaluated from top to bottom, and the first matching policy is used
Why this is correct
FortiGate firewall policies are evaluated sequentially from the top of the policy list. The first policy whose source, destination, service, and other matching criteria align with the session's attributes is selected and enforced. Because evaluation stops at the first match, placing more specific rules above broader ones is critical for proper traffic control.
- ✗
Policies are evaluated based on a priority number assigned to each policy
Why it's wrong here
FortiGate does not assign a numerical priority or weight to each policy to determine its precedence. Instead, precedence is entirely determined by the policy's physical position in the ordered list, which can be moved via the GUI or CLI. There is no hidden priority field; order alone dictates which rule is evaluated first, so this statement is false.
- ✗
Policies are evaluated from bottom to top, and the last matching policy is used
Why it's wrong here
FortiGate never evaluates policies from bottom to top; the policy list is always scanned from the first rule (top) downward. As soon as a match is found, that rule is applied and no further rules are considered. A bottom-up evaluation would imply the last rule takes precedence, which contradicts FortiGate's documented first-match behavior.
- ✗
Policies are evaluated randomly to balance load
Why it's wrong here
Policy evaluation in FortiGate is fully deterministic and does not rely on random or load-balancing selection. Every session is matched against the same ordered list in the same way, ensuring consistent behavior for identical traffic. Random evaluation would break stateful firewall integrity and make security decisions unpredictable, so it is never used.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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