The correct mapping is Atomicity to 3, Consistency to 4, Isolation to 1, and Durability to 2. This is correct because each ACID property defines a specific guarantee for database transactions: Atomicity ensures a transaction is all-or-nothing, Consistency guarantees the database moves from one valid state to another while obeying all rules, Isolation makes concurrent transactions appear to execute one after the other, and Durability permanently saves committed changes so they survive failures. On the Microsoft Azure Data Fundamentals DP-900 exam, this matching question tests your foundational understanding of transactional integrity in Azure SQL Database and other relational systems. A common trap is confusing Consistency with Atomicity—remember that Atomicity is about the transaction’s completion, while Consistency is about the database’s state obeying rules. For a quick memory tip, think of the acronym A-C-I-D: All-or-nothing, Correct state, Isolated view, Data persists.
DP-900 Describe core data concepts Practice Question
This DP-900 practice question tests your understanding of describe core data concepts. 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.
Match each ACID property with its correct description. Properties: - Atomicity - Consistency - Isolation - Durability Descriptions: 1. Transactions appear to execute one after the other, even if they are concurrent. 2. Once a transaction is committed, the changes are permanently saved and survive failures. 3. A transaction either completes fully or is rolled back entirely. 4. A transaction brings the database from one valid state to another, obeying all rules. Which option correctly maps each property to its description?
Option A is correct because it accurately maps each ACID property to its definition. Atomicity ensures a transaction is all-or-nothing (3), Consistency guarantees the database moves from one valid state to another (4), Isolation makes concurrent transactions appear serial (1), and Durability ensures committed changes persist even after a failure (2). These are the standard definitions used in Azure SQL Database and other relational database systems.
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.
This incorrectly assigns atomicity to isolation, and durability to the all-or-nothing description.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse the definitions of Consistency and Atomicity, often thinking Consistency means 'all-or-nothing' rather than 'valid state transitions,' or they swap Isolation with Durability by misremembering the 'permanent save' concept.
Detailed technical explanation
How to think about this question
Under the hood, Isolation is typically implemented via locking mechanisms (e.g., row-level locks in SQL Server) or multi-version concurrency control (MVCC) to prevent dirty reads, non-repeatable reads, and phantom reads. Durability is often ensured through write-ahead logging (WAL) where transaction log records are flushed to disk before acknowledging a commit, as seen in SQL Server's transaction log. In a real-world scenario, a banking transfer uses Atomicity to ensure both debit and credit occur or neither, and Durability guarantees the transfer survives a power outage after commit.
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 cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this DP-900 question in full detail.
Describe core data concepts — This question tests Describe core data concepts — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Atomicity → 3, Consistency → 4, Isolation → 1, Durability → 2 — Option A is correct because it accurately maps each ACID property to its definition. Atomicity ensures a transaction is all-or-nothing (3), Consistency guarantees the database moves from one valid state to another (4), Isolation makes concurrent transactions appear serial (1), and Durability ensures committed changes persist even after a failure (2). These are the standard definitions used in Azure SQL Database and other relational database systems.
What should I do if I get this DP-900 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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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. In a banking application, a transaction transfers $100 from Account A to Account B. The system deducts $100 from Account A successfully, but due to a network error, the credit to Account B fails. The application rolls back the deduction from Account A, ensuring that neither account is affected. Which ACID property is being enforced?
medium
✓ A.Atomicity
B.Consistency
C.Isolation
D.Durability
Why A: Atomicity ensures that a transaction is treated as a single, indivisible unit of work. In this scenario, the deduction from Account A and the credit to Account B must both succeed or both fail entirely. When the credit to Account B fails, the system rolls back the deduction from Account A, preserving the all-or-nothing nature of the transaction. This is the core behavior of atomicity in ACID-compliant database systems like Azure SQL Database or SQL Server.
Variation 2. A banking system processes a money transfer between two accounts. The system is designed so that after the transaction is committed, the results are permanently saved and survive any subsequent system failure, such as a power outage. Which ACID property ensures this behavior?
easy
✓ A.Durability
B.Atomicity
C.Consistency
D.Isolation
Why A: Durability ensures that once a transaction is committed, its changes are permanently stored and survive system failures, such as power outages or crashes. In this banking scenario, the money transfer results are written to non-volatile storage (e.g., disk) via a write-ahead log, guaranteeing that the committed state is recoverable even after a restart.
Variation 3. A company updates a customer's address in a database. The update must ensure that all existing orders still reference a valid customer ID. The database checks the foreign key constraint and rejects the update if it would violate referential integrity. Which ACID property does this enforcement represent?
medium
A.Atomicity
✓ B.Consistency
C.Isolation
D.Durability
Why B: Consistency ensures that any database transaction brings the database from one valid state to another, preserving all defined rules, including constraints like foreign keys. In this scenario, the foreign key constraint enforcement prevents an update that would leave orphaned order records, directly upholding the consistency property by rejecting the transaction if it violates referential integrity.
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Question Discussion
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