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Data Security and Governance →mediumMultiple ChoiceObjective-mapped

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?

A
Apply a Hash transform to the sensitive columns.
Why wrong: Wrong. The 'Hash' transform applies a cryptographic hash, not masking. Hashing is irreversible and changes the data format, whereas masking preserves format and is reversible for authorized users.
B
Apply an Encrypt transform to the sensitive columns.
Why wrong: Wrong. 'Encrypt' is not a built-in transform in AWS Glue DataBrew. Encryption is managed at the storage layer, not through DataBrew transforms.
C
Apply a Delete transform to remove the sensitive columns.
Why wrong: Wrong. The 'Delete' transform removes the entire column from the dataset, which does not satisfy the requirement to mask sensitive columns while keeping them in the output.
D
Apply a Mask transform to the sensitive columns.
Correct. The 'Mask' transform obfuscates sensitive data by replacing characters with a mask character (e.g., 'X'), preserving the column structure and data type.

Full breakdown with real-world context →

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

✓

Apply a Mask transform to the sensitive columns.

Option D is correct because DataBrew provides a built-in 'Mask' transform that obfuscates sensitive data by applying masking patterns. Option A is incorrect because the Hash transform produces a hash value, which is not true masking as it can be reversed via brute force. Option B is incorrect because Encrypt is not a DataBrew transform; encryption is handled at the storage layer (e.g., S3 SSE). Option C is incorrect because Delete removes the column entirely, which may not be desired if the column is needed for analysis but just needs sensitive data hidden.

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
Wrong. The 'Hash' transform applies a cryptographic hash, not masking. Hashing is irreversible and changes the data format, whereas masking preserves format and is reversible for authorized users.
✗
Apply an Encrypt transform to the sensitive columns.
Why it's wrong here
Wrong. 'Encrypt' is not a built-in transform in AWS Glue DataBrew. Encryption is managed at the storage layer, not through DataBrew transforms.
✗
Apply a Delete transform to remove the sensitive columns.
Why it's wrong here
Wrong. The 'Delete' transform removes the entire column from the dataset, which does not satisfy the requirement to mask sensitive columns while keeping them in the output.
✓
Apply a Mask transform to the sensitive columns.
Why this is correct
Correct. The 'Mask' transform obfuscates sensitive data by replacing characters with a mask character (e.g., 'X'), preserving the column structure and data type.
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.

Trap categories for this question

Command / output trap
Wrong. The 'Delete' transform removes the entire column from the dataset, which does not satisfy the requirement to mask sensitive columns while keeping them in the output.

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.

Quick reference

AWS S3 Storage Class Comparison

Storage Class	Min Duration	Retrieval	Use Case
S3 Standard	None	Immediate	Frequently accessed data
S3 Standard-IA	30 days	Immediate	Infrequent access, rapid retrieval
S3 One Zone-IA	30 days	Immediate	Non-critical infrequent data
S3 Intelligent-Tiering	None	Immediate–hours	Unknown or changing access patterns
S3 Glacier Instant	90 days	Milliseconds	Archive with instant retrieval
S3 Glacier Flexible	90 days	Minutes–hours	Archive, flexible retrieval
S3 Glacier Deep Archive	180 days	Hours	Long-term compliance archive

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.

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FAQ

Questions learners often ask

What does this DEA-C01 question test?

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 D is correct because DataBrew provides a built-in 'Mask' transform that obfuscates sensitive data by applying masking patterns. Option A is incorrect because the Hash transform produces a hash value, which is not true masking as it can be reversed via brute force. Option B is incorrect because Encrypt is not a DataBrew transform; encryption is handled at the storage layer (e.g., S3 SSE). Option C is incorrect because Delete removes the column entirely, which may not be desired if the column is needed for analysis but just needs sensitive data hidden.

What should I do if I get this DEA-C01 question wrong?

What is the key concept behind this question?

CIDR notation defines the prefix length.

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