The answer is the Modify effect. This is the correct choice because the Modify effect allows Azure Policy to automatically add or alter a tag on a resource during creation or update without blocking the operation, which directly matches the requirement to auto-add a missing 'CostCenter' tag with a default value of 'Unassigned' while still permitting resource creation. On the Microsoft Azure Fundamentals AZ-900 exam, this scenario tests your understanding of how policy effects differ, particularly the distinction between Deny (which blocks), Append (which adds to existing properties), and Modify (which can add or change tags). A common trap is confusing Modify with Append, but remember that Append only works on arrays or objects, not simple tag values. For the exam, keep this memory tip handy: "Modify can make or change a tag; Append is only for the array bag."
AZ-900 Describe Azure management and governance Practice Question
This AZ-900 practice question tests your understanding of describe azure management and governance. 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 company uses Azure Policy to enforce resource tagging. The governance team creates a policy that requires all resources in a subscription to have a 'CostCenter' tag. However, the team does not want to block resource creation if the tag is missing. Instead, they want the policy to automatically add the tag with a default value of 'Unassigned' to any new resource that is created without the tag. Which Azure Policy effect should the team configure in the policy definition?
Why wrong: Incorrect. The Deny effect blocks resource creation if the condition is not met, but the scenario requires automatic addition of the tag, not blocking.
B
Audit
Why wrong: Incorrect. The Audit effect creates a compliance alert but does not automatically add the tag.
C
DeployIfNotExists
Why wrong: Incorrect. DeployIfNotExists is used to deploy a resource if it is missing (e.g., an extension or agent). It is not designed to modify tags on a resource during creation.
D
Modify
Correct. The Modify effect can add, update, or remove tags (or other properties) on existing or newly created resources. It can automatically add the 'CostCenter' tag with a default value without blocking the creation.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Modify
The Modify effect is correct because it allows Azure Policy to automatically add or change a tag on a resource during creation or update without blocking the operation. This matches the requirement to add the 'CostCenter' tag with a default value of 'Unassigned' to any new resource missing it, while still permitting resource creation.
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.
✗
Deny
Why it's wrong here
Incorrect. The Deny effect blocks resource creation if the condition is not met, but the scenario requires automatic addition of the tag, not blocking.
✗
Audit
Why it's wrong here
Incorrect. The Audit effect creates a compliance alert but does not automatically add the tag.
✗
DeployIfNotExists
Why it's wrong here
Incorrect. DeployIfNotExists is used to deploy a resource if it is missing (e.g., an extension or agent). It is not designed to modify tags on a resource during creation.
✓
Modify
Why this is correct
Correct. The Modify effect can add, update, or remove tags (or other properties) on existing or newly created resources. It can automatically add the 'CostCenter' tag with a default value without blocking the creation.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is confusing DeployIfNotExists with Modify, as both can remediate non-compliance, but DeployIfNotExists deploys a separate resource (like an extension) while Modify directly changes properties of the evaluated resource itself.
Trap categories for this question
Scenario analysis trap
Incorrect. The Deny effect blocks resource creation if the condition is not met, but the scenario requires automatic addition of the tag, not blocking.
Detailed technical explanation
How to think about this question
The Modify effect uses a 'roleDefinitionIds' parameter to grant the policy assignment the necessary permissions (e.g., Contributor) to alter the resource during creation or update. Under the hood, Azure Policy intercepts the resource creation request and applies the modification before the resource is fully provisioned, ensuring the tag is present from the start. This is distinct from DeployIfNotExists, which runs a separate deployment task after the resource exists.
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 startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this AZ-900 question in full detail.
Describe Azure management and governance — This question tests Describe Azure management and governance — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Modify — The Modify effect is correct because it allows Azure Policy to automatically add or change a tag on a resource during creation or update without blocking the operation. This matches the requirement to add the 'CostCenter' tag with a default value of 'Unassigned' to any new resource missing it, while still permitting resource creation.
What should I do if I get this AZ-900 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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