The answer is that the VM was created without an external IP address, which directly causes the timeout when trying to access nginx from the internet. Without a public IP, the VM exists solely on a private network within Google Cloud, meaning internet traffic has no routable path to reach its private IP, even if firewall rules permit HTTP traffic and nginx is running. On the Google Professional Cloud Architect exam, this scenario tests your understanding of network connectivity fundamentals—specifically that a VM must have an external IP or be fronted by a Cloud NAT, load balancer, or VPN to be reachable from the internet. A common trap is assuming firewall rules alone enable public access; they only control traffic that can already reach the VM. Remember the memory tip: no external IP equals no internet route, so the packet never arrives—it’s not blocked, it’s lost.
Google PCA Design and plan a cloud solution architecture Practice Question
This PCA practice question tests your understanding of design and plan a cloud solution architecture. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
Refer to the exhibit. An architect created a VM instance using the above command. After the instance starts, the architect tries to access the nginx default page from the internet but gets a timeout. What is the most likely reason?
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
✓
The VM was created without an external IP address
The most likely reason for the timeout is that the VM was created without an external (public) IP address. Without an external IP, the VM is not directly reachable from the internet, even if nginx is running and firewall rules allow HTTP traffic. The timeout occurs because the internet has no route to the VM's private IP address.
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 VM is in a subnet without a Cloud NAT
Why it's wrong here
Even with Cloud NAT, the VM has no external IP and cannot be accessed from the internet inbound.
✗
The firewall rule allowing HTTP traffic is missing
Why it's wrong here
The default VPC includes a default-allow-httpfirewall rule for port 80.
✗
The startup script failed to install nginx
Why it's wrong here
The startup script is correctly formatted and should install nginx successfully.
✓
The VM was created without an external IP address
Why this is correct
The 'no-address' flag omits the external IP, making the VM unreachable from the internet.
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.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the distinction between connectivity failures caused by missing firewall rules (which produce connection refused or dropped packets) versus missing external IP addresses (which produce timeouts because the host is unreachable).
Detailed technical explanation
How to think about this question
In Google Cloud, a VM without an external IP address resides entirely on a private network and can only be reached from within the VPC or via a VPN/Direct Interconnect. The internet cannot route to private IP addresses (RFC 1918), so any inbound HTTP request will time out at the network edge. Even if a firewall rule permits ingress on TCP port 80, the packet is dropped before it can be evaluated because there is no public IP assigned to the VM's network interface.
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.
Design and plan a cloud solution architecture — This question tests Design and plan a cloud solution architecture — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The VM was created without an external IP address — The most likely reason for the timeout is that the VM was created without an external (public) IP address. Without an external IP, the VM is not directly reachable from the internet, even if nginx is running and firewall rules allow HTTP traffic. The timeout occurs because the internet has no route to the VM's private IP address.
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.
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