The correct answer is to use the metadata block with the key 'startup-script' and the script content as the value. This works because Terraform’s google_compute_instance resource directly supports a metadata argument, and when you set the key to startup-script, Compute Engine automatically executes that script during the instance’s first boot sequence. On the Google Professional Cloud Developer exam, this question tests your understanding of how to automate software installation at launch using Infrastructure as Code, and it’s a common trap to confuse cloud-init (which is not native to Compute Engine) or to reach for gcloud commands instead of Terraform’s declarative syntax. The key distinction is that Terraform uses metadata, not user-data or cloud-init, to pass startup scripts. Memory tip: think “metadata key equals startup-script” — if you see any other key or method in the options, it’s likely a distractor.
PCD Deploying applications Practice Question
This PCD practice question tests your understanding of deploying applications. 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.
A developer wants to deploy a Compute Engine instance using Terraform. They want to run a startup script to install software. How should they provide the script?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use the metadata block with key 'startup-script' and the script content as value.
Option A is correct because Terraform's metadata block with startup-script key is standard. Option B is wrong because cloud-init is not native to Compute Engine. Option C is wrong because compute startup scripts are not in user-data. Option D is wrong because gcloud compute instances create with --metadata-from-file is not Terraform.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Use the metadata block with key 'startup-script' and the script content as value.
Why this is correct
This is the standard way to provide startup scripts in Terraform for GCP.
Related concept
Static NAT maps one inside address to one outside address.
✗
Use a cloud-init configuration file passed via user-data metadata.
Why it's wrong here
cloud-init is more common on AWS; GCP uses startup scripts.
✗
Use the user-data metadata key with the script content.
Why it's wrong here
user-data is not a standard GCP metadata key for startup scripts.
✗
Use the gcloud compute instances create command with --metadata-from-file flag.
Why it's wrong here
That is not Terraform.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
How this comes up in practice
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
What to study next
Got this wrong? Here's your next step.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related PCD NAT questions on configuration and troubleshooting.
Deploying applications — This question tests Deploying applications — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Use the metadata block with key 'startup-script' and the script content as value. — Option A is correct because Terraform's metadata block with startup-script key is standard. Option B is wrong because cloud-init is not native to Compute Engine. Option C is wrong because compute startup scripts are not in user-data. Option D is wrong because gcloud compute instances create with --metadata-from-file is not Terraform.
What should I do if I get this PCD question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related PCD NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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Question Discussion
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