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NSE4 · Question #140

Which of the following statements is correct regarding a FortiGate unit operating in NAT/Route mode?

The correct answer is B. The FortiGate unit functions as a Layer 3 device. In NAT/Route mode, a FortiGate unit operates as a Layer 3 device, performing routing and network address translation between different IP networks.

Submitted by khalil_dz· Apr 18, 2026FortiGate Deployment and System Configuration

Question

Which of the following statements is correct regarding a FortiGate unit operating in NAT/Route mode?

Options

  • AThe FortiGate unit applies NAT to all traffic.
  • BThe FortiGate unit functions as a Layer 3 device.
  • CThe FortiGate unit functions as a Layer 2 device.
  • DThe FortiGate unit functions as a router and the firewall function is disabled.

How the community answered

(37 responses)
  • A
    3% (1)
  • B
    86% (32)
  • C
    3% (1)
  • D
    8% (3)

Why each option

In NAT/Route mode, a FortiGate unit operates as a Layer 3 device, performing routing and network address translation between different IP networks.

AThe FortiGate unit applies NAT to all traffic.

While NAT is a key feature, it's typically applied to specific traffic flows (e.g., outbound Internet traffic) as configured by policies, not indiscriminately to all traffic.

BThe FortiGate unit functions as a Layer 3 device.Correct

When operating in NAT/Route mode, the FortiGate functions as a network router, handling IP addressing and routing functions at Layer 3 of the OSI model.

CThe FortiGate unit functions as a Layer 2 device.

Functioning as a Layer 2 device describes the FortiGate in Transparent (or Bridge) mode, where it primarily forwards frames without routing or IP address changes.

DThe FortiGate unit functions as a router and the firewall function is disabled.

The firewall function is integral to a FortiGate's operation in NAT/Route mode; it acts as both a router and a firewall, not with the firewall function disabled.

Concept tested: FortiGate NAT/Route operating mode

Source: https://docs.fortinet.com/document/fortigate/7.4.0/administration-guide/339401/operating-modes

Topics

#FortiGate operating modes#NAT/Route mode#Layer 3 device#Network topology

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