The correct answer is that the instance was modified manually via the AWS console. This scenario is a classic example of state drift, where the actual infrastructure has been altered outside of Terraform’s control, causing `terraform plan` to show changes even though no configuration file has been edited. When you run a plan, Terraform compares your current state file against the real-world resources; if the AMI and instance type differ from what the state expects, Terraform will propose reverting those attributes to match your configuration. On the HashiCorp Terraform Associate TF-003 exam, this question tests your understanding of drift detection and the importance of treating Terraform as the single source of truth. A common trap is assuming a configuration error or provider bug, but the key clue is that the operator has not modified the config since the last successful apply. Memory tip: “If the config didn’t change but the plan does, someone else touched the cloud.”
TF-003 Use Terraform outside the core workflow Practice Question
This TF-003 practice question tests your understanding of use terraform outside the core workflow. 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
Terraform will perform the following actions:
# aws_instance.web will be updated in-place
~ resource "aws_instance" "web" {
~ ami = "ami-abc123" -> "ami-def456"
id = "i-1234567890abcdef0"
~ instance_type = "t2.micro" -> "t2.small"
tags = {
"Name" = "web-server"
}
}
Plan: 0 to add, 1 to change, 0 to destroy.
Refer to the exhibit. An operator runs terraform plan and gets the following output. They have not modified the Terraform configuration since the last successful apply. What is the most likely cause of the planned changes?
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.
Terraform will perform the following actions:
# aws_instance.web will be updated in-place
~ resource "aws_instance" "web" {
~ ami = "ami-abc123" -> "ami-def456"
id = "i-1234567890abcdef0"
~ instance_type = "t2.micro" -> "t2.small"
tags = {
"Name" = "web-server"
}
}
Plan: 0 to add, 1 to change, 0 to destroy.
A
Terraform provider was updated to a new version.
Why wrong: Provider updates typically do not change existing resource attributes without configuration changes.
B
The instance was terminated and recreated.
Why wrong: Termination and recreation would show a destroy and add, not an in-place update.
C
Terraform state was corrupted.
Why wrong: State corruption would likely cause errors or a plan to recreate resources, not specific attribute changes.
D
The instance was modified manually via the AWS console.
Manual changes outside Terraform cause drift, leading to these proposed updates.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The instance was modified manually via the AWS console.
The plan shows changes to the AMI and instance type, which are attributes that were not changed in the configuration. This indicates drift caused by manual modifications outside Terraform. Option A is correct because manual changes via the console cause Terraform to detect differences and propose corrections.
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.
✗
Terraform provider was updated to a new version.
Why it's wrong here
Provider updates typically do not change existing resource attributes without configuration changes.
✗
The instance was terminated and recreated.
Why it's wrong here
Termination and recreation would show a destroy and add, not an in-place update.
✗
Terraform state was corrupted.
Why it's wrong here
State corruption would likely cause errors or a plan to recreate resources, not specific attribute changes.
✓
The instance was modified manually via the AWS console.
Why this is correct
Manual changes outside Terraform cause drift, leading to these proposed updates.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
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.
Trap categories for this question
Command / output trap
Termination and recreation would show a destroy and add, not an in-place update.
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
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
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 TF-003 NAT questions on configuration and troubleshooting.
Use Terraform outside the core workflow — This question tests Use Terraform outside the core workflow — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The instance was modified manually via the AWS console. — The plan shows changes to the AMI and instance type, which are attributes that were not changed in the configuration. This indicates drift caused by manual modifications outside Terraform. Option A is correct because manual changes via the console cause Terraform to detect differences and propose corrections.
What should I do if I get this TF-003 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 TF-003 NAT questions on configuration and troubleshooting.
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?
Static NAT maps one inside address to one outside address.
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