DOP-C02 Elastic Beanstalk Auto Scaling Practice Question
A startup runs a stateless web application on AWS Elastic Beanstalk with a single environment. The application uses an Amazon RDS for MySQL database instance. The startup is preparing for a marketing campaign that is expected to increase traffic by 10x. The CTO is concerned about the application's ability to handle the load and wants to ensure high availability and resilience. The current architecture has a single RDS instance (db.t3.medium) and a single Elastic Beanstalk environment with one EC2 instance (t3.medium). The startup has a limited budget but wants to improve resilience without over-provisioning. Which combination of actions should the DevOps engineer recommend? (Choose THREE.)
⚠ Common exam trap
DOP-C02 often tests the misconception that adding caching or dedicated instances is necessary for resilience, but the core actions are auto-scaling, Multi-AZ, and connection pooling; candidates may overlook RDS Proxy or choose cost-ineffective 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
✓
Switch the Elastic Beanstalk environment to a load-balanced, auto-scaled environment with a minimum of 2 instances across 2 Availability Zones.
Option C is correct because converting the single-instance Elastic Beanstalk environment to a load-balanced, auto-scaled environment with a minimum of two instances across two Availability Zones removes the single point of failure at the web tier and lets the environment scale horizontally to absorb the 10x traffic spike. Option D is correct because enabling Multi-AZ on the RDS for MySQL instance creates a synchronous standby replica in a second AZ with automatic failover, improving database resilience without requiring application changes. Option E is correct because RDS Proxy pools and shares database connections, which prevents the connection exhaustion and overhead that occur when many new EC2 instances and users open connections directly to MySQL during a traffic surge. Option A is not among the marked answers, and while caching could reduce read load, it is not required to achieve the stated high availability and resilience goals. Option B is not marked correct because dedicated instances raise cost and do not provide the multi-AZ redundancy or elasticity that the scenario demands.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Add an Amazon ElastiCache cluster to cache frequent database queries.
Why it's wrong here
Adding an ElastiCache cluster can reduce read pressure on the database, but it does not address the fundamental single points of failure in the architecture. Caching introduces a separate infrastructure component that must itself be highly available, and it does nothing to make the web application or database resilient to instance or Availability Zone failure. For a stateless web app, the correct resilience path is horizontal scaling and automatic failover, not caching.
- ✗
Use dedicated instances for the EC2 instances to ensure consistent performance.
Why it's wrong here
Dedicated instances only provide physical server isolation for compliance or licensing reasons; they do not improve availability. A single dedicated EC2 instance running in one Availability Zone still fails if that AZ experiences an outage. This option also incurs significant additional cost without delivering the redundancy or auto-scaling that a load-balanced, multi-AZ environment provides.
- ✓
Switch the Elastic Beanstalk environment to a load-balanced, auto-scaled environment with a minimum of 2 instances across 2 Availability Zones.
Why this is correct
Deploying the Elastic Beanstalk environment as a load-balanced, auto-scaling configuration with a minimum of two instances in separate Availability Zones eliminates the web tier as a single point of failure. The load balancer distributes traffic across instances and health-checks them, while Auto Scaling replaces unhealthy instances and can scale out during load spikes. This is the foundational action for high availability of stateless applications because it provides both redundancy and elasticity.
- ✓
Enable Multi-AZ deployment for the RDS instance to provide a standby in another AZ.
Why this is correct
Enabling Multi-AZ deployment for RDS provisions a synchronous standby replica in a second Availability Zone, giving the database automatic failover if the primary instance or its AZ becomes unavailable. This achieves high availability for committed transactions with zero data loss in most failover scenarios, and it is a required complement to a redundant web tier. Without it, the RDS database remains a single point of failure capable of taking down the entire application.
- ✓
Add Amazon RDS Proxy in front of the RDS instance to handle connection pooling.
Why this is correct
Amazon RDS Proxy sits between the application and the database, maintaining a pool of reusable database connections. When the web tier scales up quickly, many EC2 instances can share the same pool, preventing the database from being overwhelmed by connection limits and reducing CPU/memory pressure. It also makes failover to a Multi-AZ standby faster and more reliable by handling connection draining, which directly improves the resilience of the whole system under variable load.
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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
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