Question 237 of 519

Interact with Terraform modules →hardMultiple ChoiceObjective-mapped

Quick Answer

The answer is that the root module has a variable called instance_type set to "t2.nano" that is being passed to the module. This occurs because when a root module declares a variable with the same name as a module input, and that variable is referenced in the module block (e.g., `instance_type = var.instance_type`), the root variable’s value overrides the module’s default—even if the module block does not explicitly set the argument. This tests your understanding of variable precedence in Terraform: module defaults are only used when no value is supplied by the calling module, and root-level variables take priority. On the HashiCorp Terraform Associate TF-003 exam, this is a common trap where candidates assume module defaults are always applied unless explicitly overridden. Remember the key rule: “A root variable with the same name as a module input will silently override the module default if passed in the module block.” Memory tip: think of the root module as the boss—its variable values always win over a module’s defaults.

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.

Your team is developing a custom module for creating EC2 instances with attached EBS volumes. The module variables are: instance_type (default "t2.micro"), ami (required), volume_size (default 8), volume_type (default "gp2"). Another team uses this module to create a web server. In their root module, they call the module without any explicit instance_type override, but they do set other variables. After applying, the web server is created with instance_type "t2.nano" instead of the expected "t2.micro". They confirm that the module still has the default "t2.micro". What is the most likely explanation?

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.

Question 1hardmultiple choice

Read the full NAT/PAT explanation →

A
The module's instance_type variable uses a default that is "t2.nano" but the root module overrode it with a variable from its own context.
Why wrong: This contradicts the given fact that the module's default is "t2.micro".
B
The instance_type variable is not defined in the module's variables.tf, so it uses a default from the AWS provider.
Why wrong: If the variable is not defined, Terraform would return an error, not silently use a different value.
C
The root module has a variable called instance_type set to "t2.nano" that is being passed to the module.
If the root module defines or inherits an instance_type variable with value "t2.nano", and the module block passes it (e.g., instance_type = var.instance_type), that overrides the module's default.
D
The module's variable default was changed to "t2.nano" in a new version.
Why wrong: The scenario states the module's default is still "t2.micro".

Full breakdown with real-world context →

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

✓

The root module has a variable called instance_type set to "t2.nano" that is being passed to the module.

Option B is correct. The root module likely has a variable named instance_type (perhaps declared elsewhere or from a parent module) that is being passed implicitly or explicitly to the module. Even if not explicitly set in the module block, if the root module's configuration includes something like `instance_type = var.instance_type` and that variable defaults to "t2.nano", it would override the module's default. Option A is contradicted by the scenario. Option C would cause an error. Option D is confusing; the module default is not being used.

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 module's instance_type variable uses a default that is "t2.nano" but the root module overrode it with a variable from its own context.
Why it's wrong here
This contradicts the given fact that the module's default is "t2.micro".
✗
The instance_type variable is not defined in the module's variables.tf, so it uses a default from the AWS provider.
Why it's wrong here
If the variable is not defined, Terraform would return an error, not silently use a different value.
✓
The root module has a variable called instance_type set to "t2.nano" that is being passed to the module.
Why this is correct
If the root module defines or inherits an instance_type variable with value "t2.nano", and the module block passes it (e.g., instance_type = var.instance_type), that overrides the module's default.
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 module's variable default was changed to "t2.nano" in a new version.
Why it's wrong here
The scenario states the module's default is still "t2.micro".

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

Scenario analysis trap
The scenario states the module's default is still "t2.micro".

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.

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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 — Static NAT maps one inside address to one outside address..

What is the correct answer to this question?

The correct answer is: The root module has a variable called instance_type set to "t2.nano" that is being passed to the module. — Option B is correct. The root module likely has a variable named instance_type (perhaps declared elsewhere or from a parent module) that is being passed implicitly or explicitly to the module. Even if not explicitly set in the module block, if the root module's configuration includes something like `instance_type = var.instance_type` and that variable defaults to "t2.nano", it would override the module's default. Option A is contradicted by the scenario. Option C would cause an error. Option D is confusing; the module default is not being used.

What should I do if I get this TF-003 question wrong?

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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