The correct answer is to create an Azure AD group for each customer, add users to the group, and assign ACLs to the group on the customer folder. This works because Azure Data Lake Storage Gen2 fine-grained access control with ACLs and Azure AD groups leverages POSIX-like permissions that can be applied at the directory or file level, and by using groups instead of individual users, you achieve scalable administration even with thousands of customers. On the Microsoft Azure Data Engineer Associate DP-203 exam, this scenario tests your understanding of how to combine Azure AD security groups with ACLs to enforce least privilege without manual overhead—a common trap is trying to assign ACLs directly to users or using RBAC alone, which lacks the granularity for per-customer isolation. Remember the key principle: groups scale, users do not. Memory tip: think “Group per folder, not user per ACL.”
DP-203 Design and implement data storage Practice Question
This DP-203 practice question tests your understanding of design and implement data storage. 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 a data engineer for a financial services company. The company uses Azure Data Lake Storage Gen2 as its data lake. You have a directory structure where each customer has a folder containing transaction files in CSV format. The security team requires that each customer's data be accessible only to that customer's users. You need to implement fine-grained access control using Azure Data Lake Storage Gen2's POSIX-like ACLs. However, you have thousands of customers, and managing ACLs individually is not feasible. What should you do?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create an Azure AD group for each customer, add users to the group, and assign ACLs to the group on the customer folder
Option D is correct because Azure Data Lake Storage Gen2 supports POSIX-like ACLs that can be assigned to Azure AD security groups. By creating one Azure AD group per customer, adding the customer's users to that group, and then assigning the group the appropriate read/execute ACLs on the customer's folder, you achieve scalable, fine-grained access control without managing thousands of individual user ACLs. This approach aligns with the principle of least privilege and simplifies administration.
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.
✗
Create a shared access signature (SAS) token for each customer and distribute it securely
Why it's wrong here
SAS tokens are not suitable for fine-grained RBAC and are hard to manage at scale.
✗
Use POSIX ACLs on each customer folder, assigning permissions to individual user identities
Why it's wrong here
This approach does not scale to thousands of customers.
✗
Use row-level security in Azure Data Lake Storage Gen2
Why it's wrong here
Row-level security is not a feature of ADLS Gen2; it uses ACLs and RBAC at the file/folder level.
✓
Create an Azure AD group for each customer, add users to the group, and assign ACLs to the group on the customer folder
Why this is correct
Group-based ACL assignment is scalable and manageable.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse row-level security (a SQL-based feature) with file-system access control in Azure Data Lake Storage Gen2, or they mistakenly believe that SAS tokens can provide granular directory-level isolation, when in fact SAS tokens operate at the container or storage account level and cannot enforce per-folder ACLs.
Detailed technical explanation
How to think about this question
Under the hood, Azure Data Lake Storage Gen2 implements a hierarchical namespace that supports POSIX-compliant ACLs with a maximum of 32 ACL entries per file or directory (including the owning user, owning group, and named users/groups). Using Azure AD groups as security principals allows you to bypass this limit by nesting users within groups, and ACLs are evaluated at the directory level, with inheritance flags (default ACLs) automatically propagating permissions to child items. In a real-world scenario, you would use the `az storage fs access set` command or the Azure portal to assign `--permissions rwx` to the group on the customer folder, ensuring that only members of that group can list and read the contents.
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 DP-203 question in full detail.
Design and implement data storage — This question tests Design and implement data storage — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Create an Azure AD group for each customer, add users to the group, and assign ACLs to the group on the customer folder — Option D is correct because Azure Data Lake Storage Gen2 supports POSIX-like ACLs that can be assigned to Azure AD security groups. By creating one Azure AD group per customer, adding the customer's users to that group, and then assigning the group the appropriate read/execute ACLs on the customer's folder, you achieve scalable, fine-grained access control without managing thousands of individual user ACLs. This approach aligns with the principle of least privilege and simplifies administration.
What should I do if I get this DP-203 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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