AZ-400 Practice Question: Design and implement build and release pipelines
Your Azure DevOps project uses Git for source control. You want to enforce that all code changes are reviewed before merging into the main branch. Which branch policy should you enable?
⚠ Common exam trap
AZ-400 often tests the confusion between build validation policies (CI gates) and reviewer policies (human approval), leading candidates to choose 'Require a successful build' when the question explicitly asks for code review.
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
✓
Require a minimum number of reviewers.
The 'Require a minimum number of reviewers' branch policy in Azure DevOps enforces that a specified number of approvers must sign off before a pull request can be completed, directly satisfying the requirement that all code changes are reviewed before merging. This policy can be set on the main branch and optionally reset votes on new pushes. It is the standard mechanism for mandatory code review in Azure Repos.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Allow only comment resolution.
Why it's wrong here
This branch policy only controls whether comment threads must be resolved before a merge, but it does not require any independent human approval. A developer could dismiss or resolve comments without the changes being reviewed by another person, so it fails to enforce a proper code review process.
- ✗
Require a successful build before merging.
Why it's wrong here
Build validation runs a CI pipeline and blocks a merge if the build or tests fail, but it only verifies code quality from an automated perspective. It does not require any human to review or approve the changes, so a successful build alone cannot enforce a code review before merging.
- ✗
Limit merge types to squash merge.
Why it's wrong here
Limiting merge types to squash merge only affects how commit history is collapsed into a single commit when the pull request is completed. This simplifies history but does not introduce any requirement for reviewers or approvals, so it does not enforce code review.
- ✓
Require a minimum number of reviewers.
Why this is correct
Setting a minimum number of reviewers is the branch policy that directly enforces code review: a pull request cannot be completed until the specified number of distinct users have explicitly approved it. This ensures that changes receive independent human verification before they are merged into the target branch.
Go deeper
Related to this question
Learn chapter
Source Control Strategy Design
Key term
Code review
A code review is a systematic examination of source code by one or more developers to find defects, improve quality, and enforce coding standards before it is merged into the main codebase.
Key term
Azure Repos
Azure Repos is a set of version control tools that allow teams to manage their source code, track changes, and collaborate on software projects using Git or Team Foundation Version Control (TFVC) within the Microsoft Azure ecosystem.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Microsoft exam blueprint
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