AZ-900 Describe cloud concepts Practice Question
What does 'high availability' mean in Azure?
⚠ Common exam trap
Test-takers frequently confuse high availability with scalability or disaster recovery, mistakenly thinking that scaling up (Option C) or data protection (Option D) directly ensures uptime, whereas high availability is specifically about minimizing downtime through redundancy and failover.
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
✓
Services that remain operational and accessible with minimal planned or unplanned downtime
High availability in Azure refers to the ability of services and resources to remain operational and accessible despite failures, with minimal planned or unplanned downtime. It is achieved through redundancy, fault tolerance, and automatic failover mechanisms, such as Azure Availability Zones and Availability Sets, which ensure that if one component fails, another takes over without significant interruption.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Resources that are accessible from any device regardless of operating system
Why it's wrong here
Accessibility from any device regardless of operating system describes cross-platform support, which is a feature of web and mobile applications, not high availability. High availability is measured in terms of uptime and resilience to failures, not the breadth of device compatibility. An app can be accessible from many OSes yet still be unavailable during an outage, so this option is incorrect.
- ✓
Services that remain operational and accessible with minimal planned or unplanned downtime
Why this is correct
This statement correctly defines high availability (HA) as the ability of a service to remain operational and accessible with minimal downtime—whether planned, such as maintenance windows, or unplanned, such as hardware failures. HA is achieved through redundancy across fault and update domains, load balancing, and automatic failover to ensure that any single point of failure does not disrupt service. Azure's Service Level Agreements (SLAs) quantify this as a percentage of uptime, making this the right answer.
- ✗
Resources that can be scaled up to handle maximum load
Why it's wrong here
Scaling resources vertically to handle maximum load describes scalability, specifically adding compute or memory to meet peak demand. High availability, by contrast, focuses on maintaining service continuity through redundant components and automatic failover, not on increasing capacity. Even a fully scaled-up resource can experience downtime if it lacks redundancy, so this option is incorrect.
- ✗
Data that is encrypted and protected from unauthorized access
Why it's wrong here
Encrypting data and preventing unauthorized access addresses confidentiality and integrity, which are core security requirements rather than availability. High availability is defined by the ability to keep the service operational and reachable despite failures, not by safeguarding data from malicious actors. Security mechanisms like encryption do not inherently reduce downtime or improve fault tolerance.
Go deeper
Related to this question
Learn chapter
High Availability and Scalability
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.
Key term
High availability
High availability is a system design approach that aims to keep applications and services operational and accessible with minimal downtime, even when some components fail.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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