AZ-900 Describe cloud concepts Practice Question
Which cloud characteristic ensures data remains accessible and readable even when stored for long periods?
⚠ Common exam trap
Many candidates confuse availability (uptime/accessibility) with durability (data integrity over time), as both terms sound similar but address fundamentally different guarantees in cloud SLAs.
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
✓
Durability
Durability is the cloud characteristic that guarantees data remains intact and readable over extended periods, even in the face of hardware failures or bit rot. Cloud providers achieve this through data replication (e.g., Azure Storage's Locally Redundant Storage (LRS) or Geo-Redundant Storage (GRS)) and erasure coding, ensuring that stored objects survive individual disk or node failures. This is distinct from availability, which focuses on uptime and access, not long-term data integrity.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Scalability
Why it's wrong here
Scalability is the capacity to handle increased workload by adding resources, either by scaling up to a larger virtual machine or scaling out to more instances. Scaling in Azure can improve performance and availability under load, but it does not create additional copies of data or protect data from loss. The need for long-term data preservation is unrelated to the system's ability to grow, so scalability is not the correct answer.
- ✓
Durability
Why this is correct
Durability is the property that assures data, once committed, will not be lost or corrupted even when hardware fails, accomplished through redundant copies, erasure coding, and cross-region replication. Azure achieves this with options like locally redundant storage (LRS), zone-redundant storage (ZRS), and geo-redundant storage (GRS), each providing a different level of persistence. Because the question asks about ensuring data is preserved over time, durability exactly matches the required guarantee.
- ✗
Availability
Why it's wrong here
Availability refers to a system's ability to remain accessible and operational when users need it, typically measured as uptime percentage and governed by fault tolerance and load balancing. In Azure, availability ensures that storage or services continue to respond without interruption, but it does not guarantee that data survives permanent disasters such as a datacenter fire or flooded rack. The question's focus on data being preserved indefinitely points to durability rather than accessibility, so availability is incorrect.
- ✗
Performance
Why it's wrong here
Performance describes how quickly a storage solution can read or write data, quantified by metrics such as latency, throughput, and IOPS. While a high-performance system can process transactions rapidly, it provides no inherent assurance that data will remain intact after a hardware failure or that it can be recovered years later. The scenario is about long-term preservation, not speed or responsiveness, making performance an incorrect answer.
Go deeper
Related to this question
Learn chapter
What is Cloud Computing?
Key term
Geo-redundant storage
Geo-redundant storage is a data storage strategy that automatically copies and maintains data in at least two geographically separated locations to protect against regional disasters and ensure high availability.
Key term
Availability
Availability is the measure of how often a system or service is operational and accessible when needed, typically expressed as a percentage of uptime.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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