← DOP-C02·Amazon Web Services

Question 553 of 1,740

Resilient Cloud Solutions →hardMultiple ChoiceObjective-mapped

Quick Answer

The correct combination is implementing Amazon RDS Proxy for connection management and adding read replicas to offload read traffic. RDS Proxy directly addresses the root cause of connection exhaustion during failovers by maintaining a warm, managed connection pool that automatically reconnects to the new primary after a Multi-AZ event, preventing the SQLTimeoutException and CJCommunicationsException seen in the logs. Adding read replicas reduces load on the primary, lowering the risk of slow queries triggering unresponsiveness and failover. On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this scenario tests your understanding of how RDS Proxy decouples application connections from database endpoints, a key pattern for high availability. A common trap is to propose scaling the instance or rewriting the connection pool logic, but RDS Proxy requires minimal application changes and is more cost-effective. Memory tip: think of RDS Proxy as a "connection bouncer" that keeps the pool alive while the database swaps out the primary.

DOP-C02 Resilient Cloud Solutions Practice Question

This DOP-C02 practice question tests your understanding of resilient cloud solutions. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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 critical e-commerce platform on AWS. The architecture includes an Application Load Balancer (ALB) that distributes traffic to a fleet of EC2 instances in an Auto Scaling group across three Availability Zones. The instances run a Java application that connects to an Amazon RDS Multi-AZ MySQL database. The application also uses Amazon ElastiCache for Redis for session caching. The company recently experienced a severe outage where the ALB's 5xx error rate spiked to 100% for 45 minutes. The root cause was a combination of a slow-running query on the RDS primary instance and a subsequent failover that caused the application to lose connections to the database. The failover happened because the slow query caused the primary to become unresponsive, triggering a Multi-AZ failover. During the failover, the application's connection pool exhausted, and new connections failed. The application logs show a high rate of 'java.sql.SQLTimeoutException' and 'com.mysql.cj.exceptions.CJCommunicationsException'. The DevOps team needs to implement a long-term solution that minimizes the impact of similar incidents. The solution must be cost-effective and require minimal application changes. Which combination of actions should the DevOps team take?

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

Clue: "primary"
Why it matters: Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.

Question 1hardmultiple choice

Read the full NAT/PAT explanation →

A
Implement Amazon RDS Proxy to manage database connections and add read replicas to offload read traffic.
RDS Proxy handles connection pooling and failover seamlessly, reducing connection timeouts during failover. Read replicas reduce load on the primary, preventing slow queries from causing failovers.
B
Use an Auto Scaling policy for EC2 based on RDS connection count and implement a read replica for the primary.
Why wrong: Auto Scaling based on connection count is not a standard metric and does not solve connection pooling during failover.
C
Configure Multi-AZ RDS with a synchronous standby and use Amazon RDS for MySQL with enhanced monitoring.
Why wrong: Multi-AZ is already in use; the issue is connection management, not the failover mechanism.
D
Increase the instance size of the RDS primary and enable Performance Insights to identify slow queries.
Why wrong: Increasing instance size does not address connection exhaustion during failover and is not cost-effective.

Full breakdown with real-world context →

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

✓

Implement Amazon RDS Proxy to manage database connections and add read replicas to offload read traffic.

Amazon RDS Proxy is the correct solution because it efficiently manages database connection pooling, reducing the likelihood of connection exhaustion during failovers. By maintaining a warm connection pool and automatically reconnecting to the new primary after a Multi-AZ failover, RDS Proxy minimizes application-side connection timeouts and errors like SQLTimeoutException and CJCommunicationsException. Adding read replicas offloads read traffic, reducing the load on the primary and mitigating the risk of slow queries causing unresponsiveness. This combination requires minimal application changes and is cost-effective compared to scaling the primary instance.

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.

✓
Implement Amazon RDS Proxy to manage database connections and add read replicas to offload read traffic.
Why this is correct
RDS Proxy handles connection pooling and failover seamlessly, reducing connection timeouts during failover. Read replicas reduce load on the primary, preventing slow queries from causing failovers.
Clue confirmation
The clue word "primary" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use an Auto Scaling policy for EC2 based on RDS connection count and implement a read replica for the primary.
Why it's wrong here
Auto Scaling based on connection count is not a standard metric and does not solve connection pooling during failover.
✗
Configure Multi-AZ RDS with a synchronous standby and use Amazon RDS for MySQL with enhanced monitoring.
Why it's wrong here
Multi-AZ is already in use; the issue is connection management, not the failover mechanism.
✗
Increase the instance size of the RDS primary and enable Performance Insights to identify slow queries.
Why it's wrong here
Increasing instance size does not address connection exhaustion during failover and is not cost-effective.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates often focus on scaling the database (e.g., increasing instance size or adding read replicas) to fix performance issues, but overlook the critical connection management problem that causes application-level timeouts during failover, which RDS Proxy directly addresses.

Detailed technical explanation

How to think about this question

RDS Proxy uses a connection multiplexing technique where it maintains a persistent pool of connections to the database, allowing the application to reuse connections without opening new ones. During a Multi-AZ failover, RDS Proxy automatically reconnects to the new primary within seconds, while the application's existing connections remain valid, preventing SQLTimeoutException. This is particularly effective for Java applications using connection pools like HikariCP, as the proxy reduces the overhead of connection creation and tear-down, which is a common bottleneck during failover scenarios.

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.

TExam Day Tips

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 startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.

What to study next

Got this wrong? Here's your next step.

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

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FAQ

Questions learners often ask

What does this DOP-C02 question test?

Resilient Cloud Solutions — This question tests Resilient Cloud Solutions — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: Implement Amazon RDS Proxy to manage database connections and add read replicas to offload read traffic. — Amazon RDS Proxy is the correct solution because it efficiently manages database connection pooling, reducing the likelihood of connection exhaustion during failovers. By maintaining a warm connection pool and automatically reconnecting to the new primary after a Multi-AZ failover, RDS Proxy minimizes application-side connection timeouts and errors like SQLTimeoutException and CJCommunicationsException. Adding read replicas offloads read traffic, reducing the load on the primary and mitigating the risk of slow queries causing unresponsiveness. This combination requires minimal application changes and is cost-effective compared to scaling the primary instance.

What should I do if I get this DOP-C02 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

Are there clue words in this question I should notice?

Yes — watch for: "primary". Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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