The correct answer is to apply a Mask transform to the sensitive columns. AWS Glue DataBrew includes a built-in Mask transform specifically designed to obfuscate sensitive data, such as credit card numbers or personally identifiable information, by replacing characters with symbols like asterisks while preserving the data structure. This directly addresses the requirement to mask before output, unlike hashing which is irreversible and not a masking technique, or deletion which removes the column entirely. On the AWS Certified Data Engineer Associate DEA-C01 exam, this question tests your knowledge of DataBrew’s native data quality actions versus storage-layer security; a common trap is confusing Mask with Encrypt, but encryption is handled at the storage layer (e.g., S3 SSE) and is not a DataBrew transform. Remember: if you need to hide data in place, Mask is the transform—think “Mask for masking, Hash for hashing, Delete for dropping, Encrypt for storage.”
DEA-C01 Data Security and Governance Practice Question
This DEA-C01 practice question tests your understanding of data security and governance. 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.
A company uses AWS Glue DataBrew to clean and normalize data. The data contains sensitive columns that must be masked before being written to the output. Which DataBrew action should be applied?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Apply a Mask transform to the sensitive columns.
Option C is correct because DataBrew has a built-in 'Mask' transform that can obfuscate sensitive data. Option A is wrong because 'Hash' is for hashing, not masking. Option B is wrong because 'Delete' removes the column entirely. Option D is wrong because 'Encrypt' is not a DataBrew transform; encryption is handled at the storage layer.
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.
✗
Apply a Hash transform to the sensitive columns.
Why it's wrong here
Hash transforms the data but does not mask it in the traditional sense.
✗
Apply an Encrypt transform to the sensitive columns.
Why it's wrong here
DataBrew does not have an Encrypt transform; encryption is separate.
✗
Apply a Delete transform to remove the sensitive columns.
Why it's wrong here
Deleting columns removes them, not masking.
✓
Apply a Mask transform to the sensitive columns.
Why this is correct
Mask transform obfuscates data, e.g., showing only last 4 digits.
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 DEA-C01 subnetting questions on CIDR, address ranges, and subnet selection.
Data Security and Governance — This question tests Data Security and Governance — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Apply a Mask transform to the sensitive columns. — Option C is correct because DataBrew has a built-in 'Mask' transform that can obfuscate sensitive data. Option A is wrong because 'Hash' is for hashing, not masking. Option B is wrong because 'Delete' removes the column entirely. Option D is wrong because 'Encrypt' is not a DataBrew transform; encryption is handled at the storage layer.
What should I do if I get this DEA-C01 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 DEA-C01 subnetting questions on CIDR, address ranges, and subnet selection.
What is the key concept behind this question?
CIDR notation defines the prefix length.
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Question Discussion
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