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 runs a web application on EC2 instances in an Auto Scaling group behind an Application Load Balancer. The application stores session data locally on each instance. During a traffic spike, the Auto Scaling group launches new instances, but users report that they are logged out and lose session data. Which solution addresses this issue without modifying the application?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable sticky sessions (session affinity) on the Application Load Balancer.
Option D is correct because enabling sticky sessions on the ALB ensures that users are routed to the same instance, preserving session data even as instances are added or removed. Option A is wrong because increasing the cooldown period does not preserve sessions during scaling. Option B is wrong, while it offloads state to ElastiCache, it requires application changes. Option C is wrong because a larger instance size reduces scaling frequency but does not prevent session loss when instances are terminated.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Modify the application to use ElastiCache for session storage.
Why it's wrong here
This requires application code changes, which the question states should be avoided.
✓
Enable sticky sessions (session affinity) on the Application Load Balancer.
Why this is correct
Sticky sessions route users to the same instance, maintaining session data during scaling.
Related concept
Static NAT maps one inside address to one outside address.
✗
Increase the cooldown period for the Auto Scaling group.
Why it's wrong here
Cooldown delays scaling but does not preserve existing sessions.
✗
Use larger EC2 instance types to handle the traffic spike.
Why it's wrong here
Larger instances reduce scaling events but do not prevent session loss when instances are terminated.
Common exam traps
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.
Detailed technical explanation
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.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
How this comes up in practice
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
Got this wrong? Here's your next step.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related SOA-C02 NAT questions on configuration and troubleshooting.
Reliability and Business Continuity — This question tests Reliability and Business Continuity — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Enable sticky sessions (session affinity) on the Application Load Balancer. — Option D is correct because enabling sticky sessions on the ALB ensures that users are routed to the same instance, preserving session data even as instances are added or removed. Option A is wrong because increasing the cooldown period does not preserve sessions during scaling. Option B is wrong, while it offloads state to ElastiCache, it requires application changes. Option C is wrong because a larger instance size reduces scaling frequency but does not prevent session loss when instances are terminated.
What should I do if I get this SOA-C02 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related SOA-C02 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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Question Discussion
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