Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
A company runs a stateful web application on a single Amazon EC2 instance. The application stores session state in memory and writes critical data to an Amazon EBS volume. The SysOps administrator needs to implement a highly available architecture that can tolerate an Availability Zone (AZ) failure. The administrator plans to use an Auto Scaling group and an Application Load Balancer (ALB). Which combination of steps is required to make the application highly available while preserving session and data durability across AZ failures?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Distractor review
Create an AMI of the current instance, configure an Auto Scaling group with a launch template that uses the AMI, and attach the existing EBS volume to new instances.
EBS volumes are AZ-specific; an EBS volume attached to an instance in one AZ cannot be attached to an instance in another AZ. This approach does not survive an AZ failure.
B
Distractor review
Create a multi-AZ Auto Scaling group and use sticky sessions (session affinity) on the ALB to tie users to specific instances.
Sticky sessions ensure a user is directed to the same instance, but if that instance fails, session data in memory is lost. It does not address AZ failure.
C
Best answer
Use an Auto Scaling group across multiple AZs, migrate session storage to Amazon ElastiCache (multi-AZ), and migrate application data from EBS to Amazon EFS (file system mounted across AZs).
ElastiCache provides a shared, cross-AZ in-memory session store. EFS provides a shared, cross-AZ file system. The Auto Scaling group launches instances in multiple AZs, and the ALB distributes traffic. This architecture survives an AZ failure.
D
Distractor review
Use an Auto Scaling group in a single AZ and use a Multi-AZ RDS instance for data storage.
A single AZ Auto Scaling group cannot tolerate an AZ failure. Multi-AZ RDS helps with data redundancy but not compute availability.
Common exam trap
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Technical deep dive
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
- Static NAT maps one inside address to one outside address.
- PAT allows many inside hosts to share one public address using ports.
- Inside local and inside global describe the private and translated addresses.
- NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
- Identify inside and outside interfaces first.
- Check whether the scenario needs static NAT, dynamic NAT or PAT.
- Do not confuse NAT matching ACLs with normal packet-filtering intent.
Related practice questions
Related SOA-C02 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A company uses Amazon CloudFront to deliver content to a global audience. The origin is an Application Load Balancer in us-east-1. The SysOps administrator wants to reduce costs by minimizing the number of requests that reach the origin server. Which action should the administrator take?
Question 2
A company runs a batch processing application on Amazon EC2 that runs for 2 hours every night. The workload can tolerate interruptions. Which EC2 purchasing option provides the lowest cost for this use case?
Question 3
A SysOps administrator needs to monitor the CPU utilization of an Amazon RDS DB instance and receive an alarm when CPU utilization exceeds 80% for 5 consecutive minutes. Which AWS service should be used to create this alarm?
Question 4
A company runs a critical web application on Amazon EC2 instances in an Auto Scaling group behind an Application Load Balancer (ALB). The application uses session stickiness (sticky sessions) to maintain user sessions. The SysOps administrator notices that when instances are replaced during a scale-in or failure event, users lose their session data. The administrator needs to preserve session data across instance failures without losing stickiness benefits. What should the administrator do?
Question 5
A company runs a production web application on a single Amazon EC2 instance. The application experiences a predictable and steady workload 24/7. The SysOps administrator wants to minimize compute costs for this instance while ensuring it remains available during the expected workload. Which EC2 purchasing option should the administrator use?
Question 6
A company has a VPC with public and private subnets. The private subnets host application servers that need to make outbound HTTPS connections to the internet. The SysOps administrator must implement a solution that provides outbound internet connectivity while preventing inbound connections from the internet. Additionally, the solution must allow the company to control which domains the application servers can access. Which solution should the administrator implement?
FAQ
Questions learners often ask
What does this SOA-C02 question test?
Static NAT maps one inside address to one outside address.
What is the correct answer to this question?
The correct answer is: Use an Auto Scaling group across multiple AZs, migrate session storage to Amazon ElastiCache (multi-AZ), and migrate application data from EBS to Amazon EFS (file system mounted across AZs). — To survive an AZ failure, the application must not depend on a single AZ's compute or storage. Session state stored in memory is lost when an instance fails, so it must be externalized to a shared, cross-AZ session store like ElastiCache. Data stored on the EBS volume is tied to a single AZ, so it must be moved to a shared, cross-AZ file system like Amazon EFS. The Auto Scaling group can launch instances across multiple AZs. Option A keeps data on EBS (which is AZ-specific). Option B uses a single AZ. Option C uses multiple AZs for compute but fails to address session and data persistence.
What should I do if I get this SOA-C02 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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