AZ-400 Design and implement source control Practice Question
This AZ-400 practice question tests your understanding of design and implement source control. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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.
You are a DevOps engineer at a company that develops a cloud-based SaaS application. The application consists of multiple microservices, each stored in its own Git repository within a single Azure DevOps project. The team has grown rapidly, and developers frequently need to make changes that span multiple services. They often complain about the overhead of managing multiple pull requests and coordinating merges across repositories. To improve efficiency, the team lead suggests consolidating all microservices into a single monorepo. However, the lead architect is concerned about the impact on build times, as the CI pipeline currently builds each service independently. You are tasked with designing a source control strategy that reduces cross-repository coordination overhead while maintaining fast, independent builds. You propose using a monorepo with a structure that allows selective building. Which approach should you recommend?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create a single monorepo with a build pipeline that uses path filters to trigger builds only for changed services
Option B is correct because using a single monorepo with path filters in the build pipeline allows you to trigger builds only for the microservices that have changed, reducing cross-repository coordination overhead while maintaining fast, independent builds. Path filters in Azure Pipelines (e.g., `paths` in YAML) enable selective triggering based on file paths, so unchanged services are not rebuilt, preserving CI efficiency.
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.
✗
Keep separate repositories but create a meta-repo that references them as submodules
Why it's wrong here
Similar to A, doesn't solve coordination overhead.
✓
Create a single monorepo with a build pipeline that uses path filters to trigger builds only for changed services
Why this is correct
Allows atomic commits across services while maintaining independent builds.
Related concept
Read the scenario before looking for a memorised answer.
✗
Keep separate repositories but use Git submodules to share code
Why it's wrong here
Submodules introduce complexity and still require multiple pull requests for cross-repo changes.
✗
Create a single monorepo with all services and a single build pipeline that builds everything
Why it's wrong here
Increases build times and reduces independence.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may confuse a monorepo with a monolithic build, assuming all code must be built together, when in fact path filters allow selective building to maintain CI speed.
Trap categories for this question
Similar concept trap
Similar to A, doesn't solve coordination overhead.
Detailed technical explanation
How to think about this question
Path filters in Azure Pipelines work by evaluating the changed files in a commit against defined include/exclude patterns (e.g., `paths: include: 'service-a/**'`). Under the hood, the pipeline trigger uses the Git diff between the commit and the previous build to decide whether to run, which is efficient for large monorepos. In a real-world scenario, you can combine path filters with multi-stage YAML pipelines to build and test only affected services, then deploy them independently, leveraging caching for unchanged dependencies.
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 cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this AZ-400 question in full detail.
Design and implement source control — This question tests Design and implement source control — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Create a single monorepo with a build pipeline that uses path filters to trigger builds only for changed services — Option B is correct because using a single monorepo with path filters in the build pipeline allows you to trigger builds only for the microservices that have changed, reducing cross-repository coordination overhead while maintaining fast, independent builds. Path filters in Azure Pipelines (e.g., `paths` in YAML) enable selective triggering based on file paths, so unchanged services are not rebuilt, preserving CI efficiency.
What should I do if I get this AZ-400 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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Question Discussion
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