Google PCA Practice Question: Analyze and optimize technical and business processes

Exhibit

{
  "resource": {
    "type": "gce_subnetwork",
    "labels": {
      "subnetwork_name": "default",
      "region": "us-central1"
    }
  },
  "severity": "ERROR",
  "textPayload": "Packet from 10.0.0.1:12345 to 10.0.0.2:80 dropped by firewall policy 'default-deny-ingress'."
}

Refer to the exhibit. The log entry is from Cloud Logging for a VPC subnetwork. What is the most likely cause of this error?

⚠ Common exam trap

Google Cloud often tests the distinction between firewall drops and routing failures; the trap here is that candidates may confuse a firewall rule drop with a missing internet gateway or an unreachable VM, but the log entry's 'firewall' field explicitly indicates a firewall decision, not a routing or connectivity issue.

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

✓

A firewall rule blocking ingress on port 80.

The log entry indicates a packet was dropped by a firewall rule. Since the destination is 10.0.0.2 on port 80 (HTTP), the most likely cause is a firewall rule blocking ingress traffic on port 80. In Google Cloud VPC, firewall rules are stateful and evaluated before any routing decisions, so a missing or misconfigured ingress rule for TCP port 80 would cause this drop.

Answer analysis

Option-by-option breakdown

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

✓
A firewall rule blocking ingress on port 80.
Why this is correct
The error message attributes the drop to firewall policy 'default-deny-ingress'.
✗
The subnetwork default has no internet gateway.
Why it's wrong here
Missing internet gateway would cause different errors, not firewall drop.
✗
The VM at 10.0.0.2 is not running.
Why it's wrong here
The log does not indicate VM state; it specifically mentions firewall drop.
✗
The packet is malformed.
Why it's wrong here
No indication of malformation; the drop is due to firewall policy.

Visual reference

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Google PCA Practice Question: Analyze and optimize technical and business processes

Exhibit

Why each option matters

Option-by-option breakdown

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