PAS-C01 Migration Practice Question
A company is migrating its on-premises web application to AWS. The application consists of a stateless web tier and a stateful database tier running on a single server. The web tier uses session data stored in the local file system. The database tier runs on MySQL. The company wants to minimize changes to the application code during migration. They plan to use Amazon EC2 for the web server and Amazon RDS for MySQL for the database. After migrating the web server to an EC2 instance and the database to RDS, users report that they are being logged out of the application frequently. What is the most likely cause of this issue?
⚠ Common exam trap
A common mix-up: candidates assume session data is automatically preserved across EC2 instance lifecycles, or they may incorrectly blame RDS connectivity or security group rules, when the real issue is the lack of a shared, durable session store for the stateless web tier.
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 web server's session data is stored locally and is lost when the EC2 instance is replaced or restarted.
The web tier stores session data in the local file system of the EC2 instance. When the instance is replaced or restarted (e.g., due to Auto Scaling, instance failure, or a maintenance event), that local session data is lost. Since the application code was not modified to use a shared session store (like ElastiCache or DynamoDB), users lose their sessions and are logged out. This is the most likely cause because the migration explicitly minimized code changes and did not address the stateless web tier requirement.
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 web server's session data is stored locally and is lost when the EC2 instance is replaced or restarted.
Why this is correct
Since the application stores sessions locally, any instance replacement leads to session loss.
- ✗
The RDS instance's backup window is causing database connections to drop.
Why it's wrong here
Backups do not cause frequent disconnections; RDS handles backups transparently.
- ✗
The application's session timeout setting was reduced during migration.
Why it's wrong here
No code changes were made, so timeout settings remain unchanged.
- ✗
The security group for the web server is blocking inbound session cookies.
Why it's wrong here
Security groups control network traffic, not application-level session cookies.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PAS-C01 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 PAS-C01 exam.