Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
A company uses Azure Synapse Analytics dedicated SQL pool to store sales data. The fact table contains billions of rows and is hash-distributed on ProductID. Queries aggregate sales by store and product for the current month and join with a small Store dimension table (10,000 rows) and a medium-sized Product dimension table (500,000 rows). The queries are slow due to data movement during joins. Which design change will most reduce data movement and improve query performance?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Distractor review
Change the fact table to round-robin distribution.
Incorrect because round-robin distributes rows evenly without any key, which can cause extensive data shuffling for joins and aggregations, often degrading performance.
B
Best answer
Replicate the Store dimension table and the Product dimension table.
Correct. Replicating small dimension tables across all distributions eliminates data movement during joins, as each distribution already has the full dimension data.
C
Distractor review
Change the hash distribution key of the fact table to StoreID.
Incorrect because changing the distribution key to StoreID would colocate data by store, but joins with Product dimension and aggregations by both store and product may still cause movement. Also, it requires repartitioning the entire table.
D
Distractor review
Implement a clustered columnstore index on the fact table.
Incorrect because a clustered columnstore index improves compression and scan performance but does not address data movement during joins, which is the root cause of the slowness.
Common exam trap
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Technical deep dive
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
- Static NAT maps one inside address to one outside address.
- PAT allows many inside hosts to share one public address using ports.
- Inside local and inside global describe the private and translated addresses.
- NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
- Identify inside and outside interfaces first.
- Check whether the scenario needs static NAT, dynamic NAT or PAT.
- Do not confuse NAT matching ACLs with normal packet-filtering intent.
Related practice questions
Related DP-900 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
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Question 2
A data engineer needs to query data stored in CSV files in Azure Data Lake Storage Gen2 using T-SQL in Azure Synapse Analytics, without loading the data into the database. Which feature should they use?
Question 3
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Question 4
A data engineer is designing a data lake architecture in Azure. They plan to first ingest raw data from various sources into a landing zone in Azure Data Lake Storage Gen2. Then they will clean, validate, and deduplicate that data in a second zone. Finally, they will create aggregated, business-ready datasets in a third zone for analysts. This layered approach is known as which architecture?
Question 5
A data engineer needs to transform large datasets stored in Azure Data Lake Storage Gen2 using Python and Apache Spark. They want a serverless compute option that automatically scales and requires no cluster management. Which Azure service should they use?
Question 6
A company collects customer feedback forms. Each form contains always-present fields like CustomerID and SubmissionDate, but also a free-text Comments field and optional fields like Rating or ProductCategory that vary between forms. How should this data be classified?
FAQ
Questions learners often ask
What does this DP-900 question test?
Static NAT maps one inside address to one outside address.
What is the correct answer to this question?
The correct answer is: Replicate the Store dimension table and the Product dimension table. — Replicating small dimension tables across all distributions eliminates the need to move data during joins, because each distribution already has a full copy of the dimension table. The Store dimension (10,000 rows) is small enough to replicate. The Product dimension is larger but may still be considered for replication if it fits within the replication threshold (default 2 GB). Hash distribution on ProductID means fact rows are spread by product, so joins with Product dimension may still cause some movement if the dimension is not replicated. However, the most impactful change is to replicate both small and medium dimensions if possible. Round-robin distribution would break the parallelism. Changing the fact table distribution to store ID would require rethinking the distribution key. A clustered columnstore index is a storage format, not a distribution strategy.
What should I do if I get this DP-900 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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