The answer is that the Terraform state file was lost or corrupted, so the instance is not tracked in state. When Terraform runs a plan, it compares the configuration against the state file to determine what exists; if the state is missing, Terraform cannot see the previously created EC2 instance, leading to a plan that attempts to create both the instance and the EIP. However, because the instance physically exists in AWS, the apply fails with an error that the instance ID does not exist—a classic symptom of state loss impact. On the HashiCorp Terraform Associate TF-003 exam, this question tests your understanding that state is the sole source of truth for resource tracking, and a common trap is assuming a successful plan guarantees a successful apply when state is out of sync. Remember the memory tip: “State is your map—lose it, and Terraform walks blind.”
TF-003 Read, generate and modify configuration Practice Question
This TF-003 practice question tests your understanding of read, generate and modify configuration. 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.
A startup uses Terraform to manage their cloud infrastructure. They have a single configuration file that defines an AWS EC2 instance. They want to add an Elastic IP (EIP) and associate it with the instance. The engineer modifies the configuration to add an `aws_eip` resource and references the instance ID. They run `terraform plan` and it shows that the EIP will be created. However, when they run `terraform apply`, they get an error: "Error: Error associating EIP: ... The instance ID 'i-1234567890abcdef0' does not exist." The instance was created successfully in a previous apply. 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
✓
The Terraform state file was lost or corrupted, so the instance is not in state.
Option B is correct because if the state was lost or corrupted, Terraform would think the instance needs to be created, but the error indicates the ID doesn't exist, which could happen if the state doesn't match reality. Option A is wrong because the instance exists. Option C is wrong because the configuration references the instance ID from the resource attribute. Option D is wrong because the instance type is not changed.
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.
✓
The Terraform state file was lost or corrupted, so the instance is not in state.
Why this is correct
state loss means Terraform doesn't know about the instance
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.
✗
The `aws_eip` resource is referencing the wrong instance attribute.
Why it's wrong here
likely correct reference
✗
The instance type has changed causing a new instance to be created.
Why it's wrong here
no change to instance type
✗
The instance was terminated manually outside Terraform.
Why it's wrong here
the error says instance ID does not exist, but it was created earlier; manual termination is possible but less likely given the error
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
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.
Read, generate and modify configuration — This question tests Read, generate and modify configuration — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The Terraform state file was lost or corrupted, so the instance is not in state. — Option B is correct because if the state was lost or corrupted, Terraform would think the instance needs to be created, but the error indicates the ID doesn't exist, which could happen if the state doesn't match reality. Option A is wrong because the instance exists. Option C is wrong because the configuration references the instance ID from the resource attribute. Option D is wrong because the instance type is not changed.
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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