Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
A company runs a critical stateful web application on Amazon EC2 instances in a single AWS region. The application stores user session data in an Amazon ElastiCache for Redis cluster. The SysOps administrator must design a disaster recovery (DR) strategy that can survive a complete regional outage with a Recovery Point Objective (RPO) of 15 minutes and a Recovery Time Objective (RTO) of 1 hour. The application must be able to redirect users to the DR region with minimal manual effort. Which combination of actions meets these requirements?
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
Use Amazon Route 53 with weighted routing to distribute traffic between the two regions. Use a global DynamoDB table for session data, and launch EC2 instances in the DR region only when a failure is detected using AWS CloudFormation StackSets.
Weighted routing does not automatically failover; it requires manual adjustment. CloudFormation StackSets would take time to provision instances, likely exceeding the 1-hour RTO. Also, the requirement mentions ElastiCache Redis, not DynamoDB.
B
Best answer
Create a read replica of the ElastiCache Redis cluster in the DR region using the native cross-region replication feature. Use Route 53 with failover routing to point to the DR region ALB when the primary health check fails. Pre-configure EC2 instances in an Auto Scaling group in the DR region.
Global Datastore for Redis provides cross-Region replication with low RPO. Pre-configured Auto Scaling groups in the DR region ensure that compute capacity is ready. Route 53 failover routing automatically redirects traffic when the primary ALB health check fails. This combination meets the RPO and RTO requirements with minimal manual effort.
C
Distractor review
Use an Amazon CloudFront distribution with multiple origins (primary and DR). Enable session stickiness at the CloudFront level. Use EC2 instances in both regions behind separate ALBs. No special data replication is needed because sessions are stored in Redis.
CloudFront does not provide cross-region failover for origins in the way Route 53 does. Session stickiness is not sufficient for DR because Redis data is not replicated across regions, so users would lose sessions after failover. RPO would be effectively longer than 15 minutes without replication.
D
Distractor review
Use EC2 instances with an Auto Scaling group in both regions. Schedule a Lambda function to take snapshots of the Redis cluster every 15 minutes and copy them to the DR region. Use Route 53 latency routing to direct users to the nearest region.
Snapshot-based replication every 15 minutes could meet the RPO, but copying snapshots and restoring them during a disaster would take more than 1 hour, exceeding the RTO. Latency routing does not provide automatic failover in a regional outage; it routes based on latency, which could still send traffic to the failed region.
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: Create a read replica of the ElastiCache Redis cluster in the DR region using the native cross-region replication feature. Use Route 53 with failover routing to point to the DR region ALB when the primary health check fails. Pre-configure EC2 instances in an Auto Scaling group in the DR region. — Achieving an RPO of 15 minutes for Redis data requires a multi-Region replication setup, such as using Global Datastore for Redis, which provides sub-minute replication lag. The EC2 instances should be pre-configured in the DR region in an Auto Scaling group, and an Application Load Balancer (ALB) should be set up. Route 53 with failover routing (health check on the primary ALB) automatically redirects traffic to the DR region when the primary region fails. Option A has an RTO violation because using CloudFormation to launch instances takes longer than 1 hour. Option B lacks automatic data replication. Option D does not ensure the DR environment is ready quickly enough.
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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