The answer is to configure the Auto Scaling group to launch instances in at least two Availability Zones, enable Multi-AZ deployment for the RDS database, and ensure the Application Load Balancer is also configured as cross-zone load balancing across those same AZs. This trio of actions is correct because surviving availability zone failure requires redundancy at every layer: the Auto Scaling group distributes EC2 capacity across AZs so that if one fails, the remaining zones absorb traffic; RDS Multi-AZ provides a synchronous standby in a different AZ for automatic failover; and the ALB, when enabled for cross-zone, can route requests to healthy targets in surviving AZs without manual intervention. On the AWS Certified Advanced Networking Specialty ANS-C01 exam, this scenario tests your understanding of layered high-availability design—a common trap is assuming the ALB alone handles AZ failure, but it only distributes traffic; it cannot create instances or fail over the database. A useful memory tip is “three layers of survival: compute, database, and load balancing—each must span at least two AZs.”
ANS-C01 Network Design Practice Question
This ANS-C01 practice question tests your understanding of network design. 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 deploying a web application across multiple Availability Zones in a single AWS Region. The application consists of an Application Load Balancer (ALB) in front of EC2 instances in an Auto Scaling group, and an Amazon RDS Multi-AZ database. The company needs to ensure that the application can survive the loss of an entire Availability Zone. Which THREE actions should they take? (Select THREE.)
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 to launch instances in at least two Availability Zones
Option B is correct because configuring the Auto Scaling group to launch instances in at least two Availability Zones ensures that if one AZ fails, the remaining AZ(s) still have healthy EC2 instances to serve traffic. This is a fundamental requirement for multi-AZ high availability, as the Auto Scaling group will automatically replace failed instances in the remaining AZs.
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.
✗
Use larger EC2 instance types to handle the load
Why it's wrong here
Larger instances do not provide AZ resilience.
✓
Configure the Auto Scaling group to launch instances in at least two Availability Zones
Why this is correct
Ensures instances are spread across AZs.
Related concept
Read the scenario before looking for a memorised answer.
✓
Configure the Application Load Balancer to be internet-facing and enable cross-zone load balancing
Why this is correct
Cross-zone load balancing helps distribute traffic across AZs.
Related concept
Read the scenario before looking for a memorised answer.
✓
Enable Multi-AZ deployment for the RDS database
Why this is correct
Multi-AZ provides automatic failover to a standby in another AZ.
Related concept
Read the scenario before looking for a memorised answer.
✗
Deploy a single NAT Gateway in one AZ for outbound traffic
Common exam trap: answer the scenario, not the keyword
AWS often tests the misconception that simply enabling cross-zone load balancing on the ALB (Option C) alone is sufficient for AZ resilience, but without the Auto Scaling group spanning multiple AZs (Option B), there would be no healthy targets in the surviving AZs to route traffic to.
Detailed technical explanation
How to think about this question
The Application Load Balancer (ALB) with cross-zone load balancing enabled distributes incoming traffic evenly across all healthy targets in all enabled AZs, regardless of which AZ the client request arrives at. This means that if one AZ fails, the ALB automatically routes traffic only to the remaining healthy instances in the other AZs, provided the Auto Scaling group has instances in those AZs. For RDS Multi-AZ, synchronous replication to a standby in a different AZ ensures automatic failover with minimal downtime, typically within 60-120 seconds, preserving database availability.
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
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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Network Design — This question tests Network Design — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Configure the Auto Scaling group to launch instances in at least two Availability Zones — Option B is correct because configuring the Auto Scaling group to launch instances in at least two Availability Zones ensures that if one AZ fails, the remaining AZ(s) still have healthy EC2 instances to serve traffic. This is a fundamental requirement for multi-AZ high availability, as the Auto Scaling group will automatically replace failed instances in the remaining AZs.
What should I do if I get this ANS-C01 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.
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 →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company is deploying a multi-tier web application across three Availability Zones in a single AWS Region. The web tier must be fault-tolerant and scale horizontally. Which network design provides the highest availability and scalability?
medium
A.Deploy a single EC2 instance in one Availability Zone with an Elastic IP address.
✓ B.Use an Application Load Balancer in front of an Auto Scaling group spanning three Availability Zones.
C.Deploy EC2 instances in a single Availability Zone and use Route 53 weighted routing.
D.Use a Network Load Balancer with a single EC2 instance in each AZ.
Why B: Option B is correct because an Application Load Balancer distributes traffic across multiple AZs and instances, providing high availability and scalability. Option A is wrong because a single instance in one AZ is not fault-tolerant. Option C is wrong because Network Load Balancer operates at layer 4 and does not support path-based routing for web applications. Option D is wrong because using only one AZ reduces fault tolerance.
Variation 2. A company has a VPC with multiple subnets across two Availability Zones. They are designing a highly available web application using an Application Load Balancer (ALB) and EC2 instances in an Auto Scaling group. Which of the following is the most resilient and cost-effective design for the network layer?
medium
A.Deploy a Network Load Balancer (NLB) in each AZ and associate them with a single ALB.
B.Deploy an ALB in one AZ and EC2 instances in the same AZ.
✓ C.Deploy a single ALB with subnets in two AZs and enable cross-zone load balancing.
D.Deploy an ALB in each AZ and use Route 53 weighted routing.
Why C: Option C is correct because deploying a single Application Load Balancer (ALB) with subnets in two Availability Zones (AZs) and enabling cross-zone load balancing provides high availability and fault tolerance at the network layer. The ALB automatically distributes incoming traffic across healthy targets in all enabled AZs, eliminating the need for multiple load balancers and reducing costs while maintaining resilience. This design leverages the ALB's native ability to handle AZ failures by routing traffic only to healthy AZs, making it both resilient and cost-effective.
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 ANS-C01 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 ANS-C01 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.