The answer is atomicity, the ACID property that guarantees the all-or-nothing behavior of a database transaction. This is correct because atomicity treats a transaction as a single, indivisible unit of work: either every operation within it is committed successfully, or none of them are applied, leaving the database unchanged if any part fails. On the Microsoft Azure Data Fundamentals DP-900 exam, this concept often appears in scenario-based questions where a transaction must roll back on error, testing your understanding of how atomicity differs from consistency (which ensures data rules) or durability (which ensures saved data persists). A common trap is confusing atomicity with isolation—remember, atomicity is about the transaction’s own completeness, not about how it interacts with other transactions. To lock in the concept, think of the mnemonic “All or Nothing” for Atomicity: if one step fails, the whole transaction is undone.
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.
A database administrator is explaining to a colleague that a database transaction must ensure that either all operations within it succeed or none of them take effect. Which ACID property is being described?
Atomicity ensures all-or-nothing execution of a transaction.
B
Consistency
Why wrong: Consistency ensures that a transaction brings the database from one valid state to another, but it does not guarantee the all-or-nothing behavior.
C
Isolation
Why wrong: Isolation ensures that concurrent transactions do not interfere with each other, not the atomicity of a single transaction.
D
Durability
Why wrong: Durability guarantees that committed changes persist even after a system failure, not the all-or-nothing behavior.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Atomicity
Atomicity ensures that a transaction is treated as a single, indivisible unit of work: either all operations within it are committed successfully, or none are applied. This is the property that guarantees the 'all-or-nothing' behavior described in the question. In Azure SQL Database or SQL Server, atomicity is enforced through the transaction log and the write-ahead logging (WAL) protocol, which records changes before they are written to disk.
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.
✓
Atomicity
Why this is correct
Atomicity ensures all-or-nothing execution of a transaction.
Related concept
Read the scenario before looking for a memorised answer.
✗
Consistency
Why it's wrong here
Consistency ensures that a transaction brings the database from one valid state to another, but it does not guarantee the all-or-nothing behavior.
✗
Isolation
Why it's wrong here
Isolation ensures that concurrent transactions do not interfere with each other, not the atomicity of a single transaction.
✗
Durability
Why it's wrong here
Durability guarantees that committed changes persist even after a system failure, not the all-or-nothing behavior.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse Atomicity with Consistency, because both involve 'correctness' — but Atomicity is about the transaction's execution as a whole, while Consistency is about the database's adherence to rules after the transaction completes.
Detailed technical explanation
How to think about this question
Under the hood, atomicity is implemented using a transaction log that records every modification. If a transaction fails before commit, the database engine uses the log to roll back all changes, restoring the original state. In distributed systems like Azure Cosmos DB, atomicity is scoped to a single partition (e.g., a stored procedure execution), and the system guarantees that either all operations within that scope succeed or none do, even across multiple documents.
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 — Atomicity ensures that a transaction is treated as a single, indivisible unit of work: either all operations within it are committed successfully, or none are applied. This is the property that guarantees the 'all-or-nothing' behavior described in the question. In Azure SQL Database or SQL Server, atomicity is enforced through the transaction log and the write-ahead logging (WAL) protocol, which records changes before they are written to disk.
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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Question Discussion
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