Question 172 of 1,546
Reliability and Business ContinuitymediumMultiple ChoiceObjective-mapped

SOA-C02 Reliability and Business Continuity Practice Question

This SOA-C02 practice question tests your understanding of reliability and business continuity. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. A key principle to apply: aWS Availability Zones are isolated locations within a region.. 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 company runs a stateless web application on Amazon EC2 instances in an Auto Scaling group with a minimum of 2 and maximum of 10 instances. The instances are behind an Application Load Balancer (ALB). The SysOps administrator needs to ensure that the application can survive the failure of an entire AWS Availability Zone (AZ) in the region. Which configuration is necessary?

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

  • Clue: "minimum / minimize"

    Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.

Question 1mediummultiple choice
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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

Configure the Auto Scaling group with subnets in at least two Availability Zones and ensure the ALB has subnets in the same AZs.

Option A is correct because deploying the Auto Scaling group across multiple Availability Zones (AZs) and ensuring the ALB has subnets in the same AZs allows the application to continue serving traffic even if one entire AZ fails. The ALB can route requests to healthy instances in the remaining AZs, and the Auto Scaling group will replace failed instances in other AZs as needed, maintaining the minimum instance count. This architecture is a fundamental pattern for high availability in AWS.

Key principle: AWS Availability Zones are isolated locations within a region.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • Configure the Auto Scaling group with subnets in at least two Availability Zones and ensure the ALB has subnets in the same AZs.

    Why this is correct

    This distributes instances across multiple AZs, so if one AZ fails, the other AZ continues serving traffic.

    Clue confirmation

    The clue word "minimum / minimize" in the question point toward this answer.

    Related concept

    AWS Availability Zones are isolated locations within a region.

  • Increase the Auto Scaling group minimum to 10 instances to absorb the failure.

    Why it's wrong here

    Running 10 instances in a single AZ still results in total failure if that AZ fails.

  • Use larger instance types to handle the load of a failed AZ.

    Why it's wrong here

    Larger instances do not provide AZ redundancy; if the only AZ fails, all instances are lost.

  • Use multiple Application Load Balancers in different AZs.

    Why it's wrong here

    Having multiple ALBs does not solve the issue if the EC2 instances are all in a single AZ; the instances still fail.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates often think increasing instance count or size alone provides high availability, but without multi-AZ distribution, a single AZ failure can still cause total application downtime.

Detailed technical explanation

How to think about this question

Under the hood, the ALB is a regional service that automatically distributes incoming traffic across targets in multiple AZs, but it requires at least one subnet in each AZ where instances are launched to function correctly. The Auto Scaling group's capacity rebalancing feature can proactively replace instances in an impaired AZ before it fully fails, but only if the group spans multiple AZs. In a real-world scenario, if the ALB subnets are not in the same AZs as the Auto Scaling group, the ALB may be unable to route traffic to healthy instances in a failed AZ, causing a complete outage.

KKey Concepts to Remember

  • AWS Availability Zones are isolated locations within a region.
  • Auto Scaling groups can launch instances across multiple specified AZs.
  • Application Load Balancers distribute traffic across targets in multiple AZs.
  • Distributing resources across AZs protects against single AZ failures.

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

AWS Availability Zones are isolated locations within a region.

Real-world example

How this comes up in practice

An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.

What to study next

Got this wrong? Here's your next step.

Review aWS Availability Zones are isolated locations within a region., then practise related SOA-C02 questions on the same topic to reinforce the concept.

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FAQ

Questions learners often ask

What does this SOA-C02 question test?

Reliability and Business Continuity — This question tests Reliability and Business Continuity — AWS Availability Zones are isolated locations within a region..

What is the correct answer to this question?

The correct answer is: Configure the Auto Scaling group with subnets in at least two Availability Zones and ensure the ALB has subnets in the same AZs. — Option A is correct because deploying the Auto Scaling group across multiple Availability Zones (AZs) and ensuring the ALB has subnets in the same AZs allows the application to continue serving traffic even if one entire AZ fails. The ALB can route requests to healthy instances in the remaining AZs, and the Auto Scaling group will replace failed instances in other AZs as needed, maintaining the minimum instance count. This architecture is a fundamental pattern for high availability in AWS.

What should I do if I get this SOA-C02 question wrong?

Review aWS Availability Zones are isolated locations within a region., then practise related SOA-C02 questions on the same topic to reinforce the concept.

Are there clue words in this question I should notice?

Yes — watch for: "minimum / minimize". Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.

What is the key concept behind this question?

AWS Availability Zones are isolated locations within a region.

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Last reviewed: Jun 11, 2026

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This SOA-C02 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the SOA-C02 exam.