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. 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 company is designing a highly available web application on AWS. The application runs on EC2 instances behind an Application Load Balancer. Which configuration ensures that the application remains available if an entire AWS Availability Zone fails?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Launch EC2 instances in at least two different Availability Zones.
Option C is correct because deploying EC2 instances across multiple Availability Zones ensures that if one AZ fails, the load balancer can route traffic to instances in the other AZ. Option A is wrong because multiple subnets in the same AZ do not protect against AZ failure. Option B is wrong because multiple VPCs add complexity but do not inherently provide AZ redundancy. Option D is wrong because a larger instance type does not address AZ failure.
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Deploy EC2 instances in multiple subnets of the same Availability Zone.
Why it's wrong here
All subnets are in the same AZ, so failure of that AZ takes down all instances.
✓
Launch EC2 instances in at least two different Availability Zones.
Why this is correct
Distributing instances across AZs provides fault isolation for AZ failures.
Use a larger EC2 instance type to handle the load.
Why it's wrong here
Instance size does not protect against AZ failure.
✗
Use EC2 instances in multiple AWS Regions.
Why it's wrong here
Multi-Region adds latency and cost; for AZ failure, multi-AZ within a Region is sufficient.
Common exam traps
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Detailed technical explanation
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
CIDR notation defines the prefix length.
Block size helps identify subnet boundaries.
Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
The required host count determines the smallest suitable subnet.
TExam Day Tips
→Write the block size before choosing the subnet.
→Check whether the question asks for hosts, subnets or a specific address range.
→Do not confuse /24, /25, /26 and /27 host counts.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
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 block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related SOA-C02 subnetting questions on CIDR, address ranges, and subnet selection.
Reliability and Business Continuity — This question tests Reliability and Business Continuity — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Launch EC2 instances in at least two different Availability Zones. — Option C is correct because deploying EC2 instances across multiple Availability Zones ensures that if one AZ fails, the load balancer can route traffic to instances in the other AZ. Option A is wrong because multiple subnets in the same AZ do not protect against AZ failure. Option B is wrong because multiple VPCs add complexity but do not inherently provide AZ redundancy. Option D is wrong because a larger instance type does not address AZ failure.
What should I do if I get this SOA-C02 question wrong?
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related SOA-C02 subnetting questions on CIDR, address ranges, and subnet selection.
What is the key concept behind this question?
CIDR notation defines the prefix length.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.