- A
The target group for the web tier does not have sticky sessions (session affinity) enabled
Sticky sessions ensure requests from a user are routed to the same instance; without it, subsequent requests may go to different instances, losing session data.
- B
The ALB is configured to disable cross-zone load balancing, causing uneven traffic distribution
Why wrong: Disabling cross-zone load balancing affects traffic distribution but does not cause session loss; sticky sessions would still work within a zone.
- C
The idle timeout of the ALB is set too low, causing sessions to expire
Why wrong: Low idle timeout would cause disconnection but not necessarily routing to different instances; users would be logged out even if sticky sessions worked.
- D
The web tier should use a Network Load Balancer (NLB) instead of an ALB for sticky sessions
Why wrong: ALB supports sticky sessions; NLB does not support HTTP session affinity based on cookies.
Quick Answer
The answer is that the target group for the web tier does not have sticky sessions (session affinity) enabled. Sticky sessions, also known as session affinity, are a feature of the Application Load Balancer that binds a user’s session to a specific target instance by using a cookie; without this setting, the ALB distributes each request to any healthy instance, causing the user to lose their in-memory session data when routed to a different web server. On the AWS Certified Solutions Architect Professional SAP-C02 exam, this scenario tests your understanding of how stateless versus stateful architectures interact with load balancers—a common trap is assuming that simply deploying behind an ALB preserves sessions, or that increasing timeouts or disabling cross-zone load balancing would fix the issue. Remember: session affinity is a target group attribute, not a listener setting; think of it as the ALB’s “memory” for which user goes to which server. A quick mnemonic is “Sticky Sessions Stick to the Target Group.”
SAP-C02 Practice Question: Accelerate Workload Migration and Modernization
This SAP-C02 practice question tests your understanding of accelerate workload migration and modernization. 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 migrating a critical 3-tier application to AWS. The application consists of a web tier, an application tier, and a PostgreSQL database. The web and application tiers are stateless and run on Linux. The company has deployed the web tier on EC2 instances behind an Application Load Balancer (ALB) across two Availability Zones. The application tier is deployed on EC2 instances in an Auto Scaling group across two Availability Zones. The PostgreSQL database is migrated to Amazon RDS for PostgreSQL with Multi-AZ deployment. The application uses sticky sessions (session affinity) to maintain user sessions on the web tier. After migration, users report that they are frequently logged out and lose session data. The web tier logs show that requests are being routed to different web instances. What is the MOST likely cause of this issue?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"most likely"Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
The target group for the web tier does not have sticky sessions (session affinity) enabled
Option B is correct: Sticky sessions must be enabled on the ALB target group to ensure requests from a user are sent to the same web instance. Option A (increased timeouts) might help but is not the root cause. Option C (disable cross-zone load balancing) would not solve session affinity across AZs. Option D (switch to NLB) is not necessary and NLB does not support HTTP features.
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.
- ✓
The target group for the web tier does not have sticky sessions (session affinity) enabled
Why this is correct
Sticky sessions ensure requests from a user are routed to the same instance; without it, subsequent requests may go to different instances, losing session data.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The ALB is configured to disable cross-zone load balancing, causing uneven traffic distribution
Why it's wrong here
Disabling cross-zone load balancing affects traffic distribution but does not cause session loss; sticky sessions would still work within a zone.
- ✗
The idle timeout of the ALB is set too low, causing sessions to expire
Why it's wrong here
Low idle timeout would cause disconnection but not necessarily routing to different instances; users would be logged out even if sticky sessions worked.
- ✗
The web tier should use a Network Load Balancer (NLB) instead of an ALB for sticky sessions
Why it's wrong here
ALB supports sticky sessions; NLB does not support HTTP session affinity based on cookies.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
- Use explanations to understand the rule behind the answer.
TExam Day Tips
- Underline the problem statement mentally.
- 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
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.
Identify which SAP-C02 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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Accelerate Workload Migration and Modernization — study guide chapter
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FAQ
Questions learners often ask
What does this SAP-C02 question test?
Accelerate Workload Migration and Modernization — This question tests Accelerate Workload Migration and Modernization — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The target group for the web tier does not have sticky sessions (session affinity) enabled — Option B is correct: Sticky sessions must be enabled on the ALB target group to ensure requests from a user are sent to the same web instance. Option A (increased timeouts) might help but is not the root cause. Option C (disable cross-zone load balancing) would not solve session affinity across AZs. Option D (switch to NLB) is not necessary and NLB does not support HTTP features.
What should I do if I get this SAP-C02 question wrong?
Identify which SAP-C02 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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 →
Same concept, more angles
2 more ways this is tested on SAP-C02
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 migrating a web application from on-premises to AWS. The application consists of a stateless web tier and a stateful application tier that stores session data in a local file system. The company wants to use AWS Elastic Beanstalk for both tiers. During a test migration, the development team notices that users are being logged out intermittently. The application tier is configured with two EC2 instances behind an internal load balancer. What should the development team do to resolve the issue?
medium- A.Enable sticky sessions (session affinity) on the application tier's load balancer.
- ✓ B.Move session storage to Amazon ElastiCache for Redis and configure the application to use it.
- C.Increase the number of instances in the web tier to reduce the load on the application tier.
- D.Store session data in Amazon DynamoDB.
Why B: Option A is correct because session data stored locally is lost when the instance is terminated or when traffic is routed to a different instance. Using ElastiCache for Redis provides a centralized session store that persists across instances. Option B is wrong because sticky sessions (session affinity) can cause load imbalance and are not a best practice. Option C is wrong because scaling the web tier does not fix the session state issue. Option D is wrong because DynamoDB is not a native session store and requires custom code.
Variation 2. A company is migrating a legacy on-premises web application to AWS. The application consists of a stateless web tier and a stateful application tier that stores session data in memory. The company wants to achieve high availability and elasticity. The migration must minimize code changes. The solutions architect proposes using an Application Load Balancer (ALB) with sticky sessions and an Auto Scaling group for the web tier. For the application tier, they plan to use an ALB with sticky sessions and an Auto Scaling group. During testing, users report that they are unexpectedly logged out and lose session data. The application logs show that requests from the same user are being sent to different instances. Which change should the solutions architect make to resolve this issue?
hard- A.Disable sticky sessions and use a Network Load Balancer instead.
- B.Migrate session state to Amazon ElastiCache for Redis.
- ✓ C.Verify that the ALB stickiness configuration is enabled and the cookie duration is appropriate.
- D.Disable cross-zone load balancing on the ALB.
Why C: Sticky sessions rely on the ALB cookie. If the cookie is not set or is not being sent back, the load balancer cannot maintain session affinity. Checking the ALB stickiness configuration ensures that the duration and cookie settings are correct. Option A is wrong because moving sessions to ElastiCache requires code changes, which the company wants to minimize. Option B is wrong because cross-zone load balancing distributes traffic evenly but does not affect stickiness. Option D is wrong because disabling stickiness would worsen the problem.
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Last reviewed: Jun 20, 2026
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