SAP-C02 Practice Question: Accelerate Workload Migration and Modernization
A company is migrating a legacy monolithic application to AWS. The application has a stateful session layer that uses local disk storage. The migration plan involves rehosting the application on Amazon EC2 instances. What architecture change should the company implement to ensure high availability and stateless application tiers?
⚠ Common exam trap
SAP-C02 often tests whether candidates confuse 'externalizing state' with 'making the tier stateless' — RDS externalizes state but is the wrong performance fit, and EBS keeps state local, so only ElastiCache satisfies both statelessness and low-latency session access.
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
✓
Use Amazon ElastiCache for session state management.
Moving session state to Amazon ElastiCache (Redis or Memcached) externalizes the stateful layer so EC2 instances become stateless and can be placed behind an ELB/ALB with Auto Scaling. This enables any instance to serve any request, supports horizontal scaling, and survives instance failure without losing sessions. ElastiCache provides the low-latency, in-memory access pattern that session lookups require.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Store session data in Amazon S3 with Transfer Acceleration.
Why it's wrong here
S3 with Transfer Acceleration stores objects, not session state, and adds latency rather than providing a shared low-latency session store. Session data belongs in ElastiCache or DynamoDB, which the application queries per request. S3 suits static asset delivery or backups, not per-request session lookups.
- ✗
Use Amazon RDS with Multi-AZ to store session data.
Why it's wrong here
RDS stores relational data, not HTTP session state, so the application tier still reads and writes sessions through a database rather than becoming stateless. It is tempting because RDS Multi-AZ provides durable, replicated storage, and it would suit persisting structured business records or user profiles that outlive a session.
- ✓
Use Amazon ElastiCache for session state management.
Why this is correct
Storing session state in Amazon ElastiCache (Redis or Memcached) externalises it from instance local disk, so any EC2 instance in the Auto Scaling group can serve any request. This removes the stateful constraint, letting the tier scale horizontally and survive instance failure behind a load balancer.
- ✗
Attach Amazon EBS volumes to each EC2 instance for session persistence.
Why it's wrong here
EBS volumes are Availability Zone-scoped and attach to a single instance, so session data stays bound to one EC2 host and cannot be shared across an Auto Scaling group. It is tempting because EBS replicates within its AZ, and it would suit a single-instance workload needing durable block storage.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
Go deeper
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Amazon Web Services exam blueprint
This SAP-C02 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 SAP-C02 exam.