- A
Use a Terraform data source in the second module to query the subnets directly.
Why wrong: This couples the second module to the cloud provider and may not reflect the exact subnets created.
- B
Define the subnet IDs as a variable in the first module and pass them to the second module via a remote state data source.
Why wrong: Variables are inputs, not outputs. Remote state is an option, but direct module output is simpler.
- C
Store the subnet IDs in a local file and use the 'file' function to read them in the second module.
Why wrong: This is fragile and not idiomatic; modules should use explicit inputs and outputs.
- D
Output the subnet IDs from the first module and reference that output as an input variable in the second module's block.
This is the correct pattern: module outputs are consumed as module input variables.
Quick Answer
The answer is to output the subnet IDs from the first module and reference that output as an input variable in the second module's block. This is correct because Terraform enforces explicit data flow between modules through input and output variables, creating a clear, dependency-aware graph that Terraform uses for parallel execution and change tracking. On the HashiCorp Terraform Associate TF-003 exam, this concept tests your understanding of module composition and the principle that modules should never access another module's resources directly—only through declared interfaces. A common trap is attempting to use data sources or hard-coded values to bridge modules, which breaks dependency tracking and can cause race conditions. Remember the golden rule: outputs are the only way out, inputs are the only way in. For a quick memory tip, think of modules as black boxes with labeled plugs (inputs) and sockets (outputs)—you must always plug an output socket into an input plug to pass data between them.
TF-003 Interact with Terraform modules Practice Question
This TF-003 practice question tests your understanding of interact with terraform modules. 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.
An engineer is refactoring a monolithic Terraform configuration into reusable modules. One module outputs a list of subnet IDs. Another module needs to use these subnet IDs to create resources. What is the best way to pass this data between modules?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"best"Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Output the subnet IDs from the first module and reference that output as an input variable in the second module's block.
Option D is correct because Terraform modules communicate through explicit input and output variables. By outputting the subnet IDs from the first module and then referencing that output as an input variable in the second module's block, you create a clear, versionable, and dependency-aware data flow. This approach avoids hidden dependencies and ensures Terraform can properly graph the resource dependencies for parallel execution.
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.
- ✗
Use a Terraform data source in the second module to query the subnets directly.
Why it's wrong here
This couples the second module to the cloud provider and may not reflect the exact subnets created.
- ✗
Define the subnet IDs as a variable in the first module and pass them to the second module via a remote state data source.
Why it's wrong here
Variables are inputs, not outputs. Remote state is an option, but direct module output is simpler.
- ✗
Store the subnet IDs in a local file and use the 'file' function to read them in the second module.
Why it's wrong here
This is fragile and not idiomatic; modules should use explicit inputs and outputs.
- ✓
Output the subnet IDs from the first module and reference that output as an input variable in the second module's block.
Why this is correct
This is the correct pattern: module outputs are consumed as module input variables.
Clue confirmation
The clue word "best" 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
HashiCorp often tests the misconception that remote state data sources are the only way to pass data between modules, when in fact direct output-to-variable passing is the simplest and most maintainable approach within a single Terraform configuration.
Trap categories for this question
Command / output trap
Variables are inputs, not outputs. Remote state is an option, but direct module output is simpler.
Detailed technical explanation
How to think about this question
Under the hood, Terraform builds a dependency graph from module outputs to module input variables, enabling it to determine the correct order of operations—the first module must be applied before the second module can resolve its inputs. A real-world scenario where this matters is when using Terraform Cloud or Enterprise, where remote state data sources introduce network latency and potential stale state, whereas direct output-to-variable passing within the same configuration is resolved entirely in-memory during planning and avoids these issues.
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 network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
- →
Interact with Terraform modules — study guide chapter
Learn the concepts, then practise the questions
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Interact with Terraform modules practice questions
Targeted practice on this topic area only
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All TF-003 questions
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HashiCorp Terraform Associate TF-003 study guide
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TF-003 practice test guide
How to use practice tests most effectively before exam day
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FAQ
Questions learners often ask
What does this TF-003 question test?
Interact with Terraform modules — This question tests Interact with Terraform modules — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Output the subnet IDs from the first module and reference that output as an input variable in the second module's block. — Option D is correct because Terraform modules communicate through explicit input and output variables. By outputting the subnet IDs from the first module and then referencing that output as an input variable in the second module's block, you create a clear, versionable, and dependency-aware data flow. This approach avoids hidden dependencies and ensures Terraform can properly graph the resource dependencies for parallel execution.
What should I do if I get this TF-003 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: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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Same concept, more angles
1 more ways this is tested on TF-003
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. You have two modules that create resources in different providers. Module A creates a VPC in AWS, Module B creates a Kubernetes cluster that requires the VPC ID. You want to ensure Module B runs after Module A but avoid hardcoding the VPC ID. Which approach is most appropriate?
hard- A.Use a data source in Module B to look up the VPC.
- ✓ B.Output the VPC ID from Module A and pass it as input to Module B.
- C.Use terraform graph to order modules.
- D.Use module dependency via depends_on in the root module.
Why B: Option B is correct because using outputs from Module A and passing them as inputs to Module B establishes both ordering and data flow. Option A (depends_on) ensures ordering but does not pass data. Option C (data source) would require the VPC to already exist. Option D (terraform graph) only visualizes, not enforces.
Last reviewed: Jun 30, 2026
This TF-003 practice question is part of Courseiva's free HashiCorp 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 TF-003 exam.
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