AZ-400 Design and implement source control Practice Question
This AZ-400 practice question tests your understanding of design and implement source control. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 uses Git-LFS to store large binary files. They observe that cloning the repository takes a long time because Git-LFS files are downloaded. How can they improve clone performance?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use the --filter=blob:none option when cloning
Option B is correct because the `--filter=blob:none` option performs a partial clone, which omits all blob objects (including Git-LFS pointer files and other large blobs) from the initial download. This significantly reduces clone time by only fetching commit and tree metadata, and then lazily downloading blobs on demand when they are actually accessed. For Git-LFS specifically, this avoids downloading the large binary files stored in LFS until they are needed, improving clone performance.
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.
✗
Use a shallow clone with depth 1
Why it's wrong here
Shallow clone reduces commit history but still downloads LFS files for the single commit.
✓
Use the --filter=blob:none option when cloning
Why this is correct
This partial clone defers downloading LFS blobs until they are accessed.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use sparse checkout to limit files in working directory
Why it's wrong here
Sparse checkout limits checked-out files but LFS is still downloaded for all files.
✗
Configure git lfs prune to run automatically
Why it's wrong here
Prune removes local LFS cache but does not affect clone time.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse shallow clones (which limit history) or sparse checkouts (which limit working tree files) with partial clones (which limit object downloads), not realizing that Git-LFS files are downloaded during checkout regardless of history depth or sparse patterns unless blob filtering is used.
Detailed technical explanation
How to think about this question
Under the hood, `--filter=blob:none` leverages Git's partial clone protocol (introduced in Git 2.19) to defer blob downloads. When a Git-LFS pointer file is accessed, Git downloads the blob (the pointer), and then Git-LFS's smudge filter triggers a separate HTTP request to the LFS storage server to fetch the actual large file. This two-step lazy fetch can still cause latency on first access, but it eliminates the upfront bulk download that makes full clones slow. In real-world scenarios with repositories containing gigabytes of binary assets, this can reduce clone time from minutes to seconds.
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
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: Use the --filter=blob:none option when cloning — Option B is correct because the `--filter=blob:none` option performs a partial clone, which omits all blob objects (including Git-LFS pointer files and other large blobs) from the initial download. This significantly reduces clone time by only fetching commit and tree metadata, and then lazily downloading blobs on demand when they are actually accessed. For Git-LFS specifically, this avoids downloading the large binary files stored in LFS until they are needed, improving clone performance.
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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