- A
Use a copy activity with a query to select only non-PII columns.
Why wrong: This omits columns but does not mask them.
- B
Use a stored procedure activity to mask data in the source before copy.
Why wrong: This modifies source data, which may not be desired.
- C
Enable staging on the copy activity to use PolyBase.
Why wrong: Staging does not provide masking.
- D
Use a mapping data flow to apply a mask transformation on PII columns.
Data flows support mask transformations.
Question 150 of 851
Applying Mask Transformations to PII Columns in ADF Data Flows
This DP-203 practice question tests your understanding of secure, monitor, and optimize data storage and data processing. 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 designing a data pipeline that uses Azure Data Factory to copy data from an Azure SQL database to Azure Data Lake Storage Gen2. The data contains personally identifiable information (PII) that must be masked. Which Data Factory feature should you use?
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
✓
Use a mapping data flow to apply a mask transformation on PII columns.
The correct answer is D because Mapping Data Flows in Azure Data Factory provide built-in transformations for data masking, such as the Mask transformation, which can obfuscate PII columns during the data flow. Option A is incorrect because a copy activity with a query can only filter columns but does not support masking; it simply selects a subset of columns without transformation. Option B is incorrect because while a stored procedure activity can execute masking logic on the source, it requires additional setup and does not integrate seamlessly with Data Factory's native transformation capabilities. Option C is incorrect because staging with PolyBase is used to improve bulk copy performance, not for data masking.
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
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 copy activity with a query to select only non-PII columns.
Why it's wrong here
This omits columns but does not mask them.
- ✗
Use a stored procedure activity to mask data in the source before copy.
Why it's wrong here
This modifies source data, which may not be desired.
- ✗
Enable staging on the copy activity to use PolyBase.
Why it's wrong here
Staging does not provide masking.
- ✓
Use a mapping data flow to apply a mask transformation on PII columns.
Why this is correct
Data flows support mask transformations.
Related concept
CIDR notation defines the prefix length.
Common exam traps
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Detailed technical explanation
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
- CIDR notation defines the prefix length.
- Block size helps identify subnet boundaries.
- Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
- The required host count determines the smallest suitable subnet.
TExam Day Tips
- Write the block size before choosing the subnet.
- Check whether the question asks for hosts, subnets or a specific address range.
- Do not confuse /24, /25, /26 and /27 host counts.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
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.
What to study next
Got this wrong? Here's your next step.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related DP-203 subnetting questions on CIDR, address ranges, and subnet selection.
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FAQ
Questions learners often ask
What does this DP-203 question test?
Secure, monitor, and optimize data storage and data processing — This question tests Secure, monitor, and optimize data storage and data processing — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Use a mapping data flow to apply a mask transformation on PII columns. — The correct answer is D because Mapping Data Flows in Azure Data Factory provide built-in transformations for data masking, such as the Mask transformation, which can obfuscate PII columns during the data flow. Option A is incorrect because a copy activity with a query can only filter columns but does not support masking; it simply selects a subset of columns without transformation. Option B is incorrect because while a stored procedure activity can execute masking logic on the source, it requires additional setup and does not integrate seamlessly with Data Factory's native transformation capabilities. Option C is incorrect because staging with PolyBase is used to improve bulk copy performance, not for data masking.
What should I do if I get this DP-203 question wrong?
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related DP-203 subnetting questions on CIDR, address ranges, and subnet selection.
What is the key concept behind this question?
CIDR notation defines the prefix length.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
1 more ways this is tested on DP-203
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. An organization is using Azure Data Factory to ingest data from multiple on-premises SQL Server databases into Azure Synapse Analytics. They need to ensure that sensitive data is masked during ingestion before landing in the staging area. What is the best approach?
hard- A.Apply an Azure Policy that masks sensitive data in Azure Synapse Analytics.
- B.Use Azure SQL Database dynamic data masking on the source databases.
- ✓ C.Use a Mapping Data Flow with derived column transformations to mask sensitive columns.
- D.Use Azure Purview to classify and mask sensitive data automatically.
Why C: Mapping Data Flow in Azure Data Factory allows you to transform data during ingestion. Using derived column transformations, you can apply masking functions (e.g., substituting characters, hashing) to sensitive columns before writing to the staging area. This approach masks data before it reaches the staging area, meeting the requirement. Option A (Azure Policy) is for compliance and cannot mask data. Option B (Dynamic Data Masking on source) masks data at query time, not during ingestion. Option D (Azure Purview) is for data governance and classification, not for masking data during a pipeline.
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Last reviewed: Jun 21, 2026
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