Google ACE Configuring Access and Security Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✓

  The VPC does not have a default route (0.0.0.0/0) to the default internet gateway.

  Why this is correct

  For Cloud NAT to work, the VPC network must contain a default route (0.0.0.0/0) whose next hop is the default internet gateway. This route is what causes outbound packets from instances to be sent to the gateway, where Cloud NAT performs the source IP translation. Without this route, packets destined for the internet have no valid next hop and are dropped, so the instances cannot reach the internet at all—Cloud NAT alone does not create routing logic.

• ✗

  The firewall rules do not allow egress traffic.

  Why it's wrong here

  In a default GCP VPC, there is an ingress allow-all and egress allow-all firewall rule, so outbound traffic is permitted unless an explicit deny rule with higher priority overrides it. Since no deny egress rule is mentioned, the lack of outbound connectivity is not due to firewall restrictions. Even if restrictive firewall rules existed, they would still need to allow traffic to traverse the NAT; but because the question points to a routing problem, firewall is not the primary cause here.

• ✗

  The Cloud Router is in a different region.

  Why it's wrong here

  Cloud NAT is a regional resource, meaning it only applies to instances in the same region as the Cloud Router and NAT configuration. If the Cloud Router is in a different region, instances in the intended region simply would not have Cloud NAT available, but they would still have internet access via their default route if one exists. In this scenario, the instances are described as private and unable to reach the internet, which points to the network having no default route at all, not a regional mismatch.

• ✗

  The instances are not assigned a network tag used by the NAT.

  Why it's wrong here

  Cloud NAT does not select instances by network tags; it applies to all instances in the region of the NAT gateway, regardless of tags. Tags are used for firewall rule targeting and are not a condition for NAT membership. Therefore, even if instances lack a specific tag, they would still be eligible for NAT if a default route and Cloud NAT are configured. The misconception that tags are required arises from confusing Cloud NAT with firewall rules, but NAT is region-wide.

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