The correct choice is B, because Terraform accesses module outputs using the syntax module.module_name.output_name, allowing you to pass outputs between modules seamlessly. When you define a VPC module and an app module, the app module can reference the VPC module’s output—such as subnet_id—by writing subnet_id = module.vpc.subnet_id, which creates a clean dependency chain. On the HashiCorp Terraform Associate TF-003 exam, this concept tests your understanding of inter-module communication and the module output attribute pattern, a frequent topic in questions about reusing infrastructure across environments. A common trap is confusing module outputs with resource attributes or forgetting to declare the source module first; options A and C use incorrect syntax like module.vpc.outputs.subnet_id or resource references, while D omits the VPC module definition entirely. To remember this, think of the module as a black box with labeled outputs—just call module.name.output_name, like accessing a property on an object.
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 team wants to reuse a VPC module across multiple environments. They need to pass outputs from one module as inputs to another. Which configuration is correct?
Correct B: module outputs are accessed as module.module_name.output_name. A and C use incorrect syntax, D misses the VPC module definition.
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
Missing the vpc module definition, causing a reference error.
Common exam traps
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Trap categories for this question
Command / output trap
.outputs is not part of the syntax; it's just module.name.output.
Detailed technical explanation
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
CIDR notation defines the prefix length.
Block size helps identify subnet boundaries.
Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
The required host count determines the smallest suitable subnet.
TExam Day Tips
→Write the block size before choosing the subnet.
→Check whether the question asks for hosts, subnets or a specific address range.
→Do not confuse /24, /25, /26 and /27 host counts.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
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.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related TF-003 subnetting questions on CIDR, address ranges, and subnet selection.
Read, generate and modify configuration — This question tests Read, generate and modify configuration — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: module "vpc" { source = "./vpc" } module "app" { source = "./app" subnet_id = module.vpc.subnet_id } — Correct B: module outputs are accessed as module.module_name.output_name. A and C use incorrect syntax, D misses the VPC module definition.
What should I do if I get this TF-003 question wrong?
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related TF-003 subnetting questions on CIDR, address ranges, and subnet selection.
What is the key concept behind this question?
CIDR notation defines the prefix length.
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Question Discussion
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