The answer is that no firewall rule allows ingress traffic to the instance. This is correct because Google Cloud VPC networks have an implied deny-all ingress rule by default, meaning any inbound traffic from the internet is automatically blocked unless a specific firewall rule explicitly permits it. In the Terraform configuration, the most likely omission is a `google_compute_firewall` resource that defines allowed protocols and ports—such as tcp:22 for SSH or tcp:80 for HTTP—and applies those rules to the instance’s network tags or service account. On the Google Professional Cloud Architect exam, this scenario tests your understanding of GCP’s default security posture and the necessity of explicit ingress rules for internet access; a common trap is assuming that simply deploying a Compute Engine instance automatically opens it to the internet. Remember the memory tip: “No rule, no route”—without a firewall rule permitting ingress, your instance remains isolated from the internet.
Google PCA Practice Question: Analyze and optimize technical and business processes
This PCA practice question tests your understanding of analyze and optimize technical and business processes. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Exhibit
Refer to the exhibit.
```
resource "type" "name" {
project = "my-project"
name = "example-instance"
machine_type = "e2-medium"
zone = "us-central1-a"
boot_disk {
initialize_params {
image = "debian-cloud/debian-11"
size = 10
type = "pd-standard"
}
}
network_interface {
network = "default"
access_config {
// Ephemeral public IP
}
}
}
```
Refer to the exhibit. A DevOps engineer created this Terraform configuration to deploy a Compute Engine instance. After applying, they notice the instance is not accessible from the internet. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
No firewall rule allows ingress traffic to the instance.
The most likely cause is that no firewall rule allows ingress traffic to the instance. By default, GCP instances are created with a VPC network that has implied deny-all ingress rules, and unless a specific firewall rule (e.g., allowing tcp:22 for SSH or tcp:80 for HTTP) is applied to the instance's network tags or service account, all inbound traffic from the internet is blocked. The Terraform configuration shown in the exhibit likely omitted a `google_compute_firewall` resource or did not assign the necessary network tags to the instance.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 machine type e2-medium does not support public IP addresses.
Why it's wrong here
Machine type does not determine public IP support.
✗
The instance is not attached to a VPC network.
Why it's wrong here
The configuration specifies the 'default' network.
✓
No firewall rule allows ingress traffic to the instance.
Why this is correct
Firewall rules are needed to allow inbound traffic; the default network may not have appropriate rules.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The boot disk size is too small to run the operating system.
Why it's wrong here
10 GB is sufficient for Debian.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that assigning a public IP automatically makes an instance internet-accessible, but the trap here is that without a corresponding ingress firewall rule, the instance remains isolated regardless of the public IP.
Detailed technical explanation
How to think about this question
In GCP, firewall rules are stateful and evaluated at the instance level based on network tags or service accounts. Even if the instance has an external IP, all inbound traffic is denied unless a firewall rule explicitly permits it (e.g., `direction: INGRESS`, `allowed: tcp:22`, `sourceRanges: 0.0.0.0/0`). A common oversight is forgetting to create the firewall rule or failing to tag the instance with the rule's target tag, which results in the instance being unreachable despite having a public IP.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this PCA question in full detail.
Analyze and optimize technical and business processes — This question tests Analyze and optimize technical and business processes — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: No firewall rule allows ingress traffic to the instance. — The most likely cause is that no firewall rule allows ingress traffic to the instance. By default, GCP instances are created with a VPC network that has implied deny-all ingress rules, and unless a specific firewall rule (e.g., allowing tcp:22 for SSH or tcp:80 for HTTP) is applied to the instance's network tags or service account, all inbound traffic from the internet is blocked. The Terraform configuration shown in the exhibit likely omitted a `google_compute_firewall` resource or did not assign the necessary network tags to the instance.
What should I do if I get this PCA question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This PCA practice question is part of Courseiva's free Google Cloud certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PCA exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.