You decide to set up Cloud NAT. After completing the configuration, you find that one of your instances is not using the Cloud NAT for outbound NAT. What is the most likely cause of this problem?

The correct answer is B. An external IP address has been configured on the instance. The existence of an external IP address on an interface always takes precedence and always performs one-to-one NAT, without using Cloud NAT. https://cloud.google.com/nat/docs/overview#specifications

Submitted by khalil_dz· Apr 18, 2026Configuring network services

Question

You decide to set up Cloud NAT. After completing the configuration, you find that one of your instances is not using the Cloud NAT for outbound NAT. What is the most likely cause of this problem?

Options

AThe instance has been configured with multiple interfaces.
BAn external IP address has been configured on the instance.
CYou have created static routes that use RFC1918 ranges.
DThe instance is accessible by a load balancer external IP address.

How the community answered

(40 responses)

A
3% (1)
B
90% (36)
C
5% (2)
D
3% (1)

Explanation

The existence of an external IP address on an interface always takes precedence and always performs one-to-one NAT, without using Cloud NAT. https://cloud.google.com/nat/docs/overview#specifications

Topics

#Cloud NAT#Outbound connectivity#External IP addresses#Network troubleshooting

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