The answer is that the number of connections exceeded the max_connections limit. The default max_connections for Aurora MySQL is calculated based on the DB instance’s memory, and for a db.r5.large with 8 GB, this value is approximately 800. When a sudden connection spike pushes active connections past this threshold, the database exhausts critical resources like memory and threads, causing it to become unresponsive rather than simply rejecting new connections. On the AWS Certified Database Specialty DBS-C01 exam, this scenario tests your understanding of how Aurora MySQL’s default parameter settings interact with instance sizing—a common trap is confusing storage or replica issues with connection limits. Remember that Aurora’s storage auto-scales seamlessly and burst balance applies only to gp2 EBS volumes, not Aurora’s cluster storage. A quick memory tip: think “800 for 8 GB”—the default max_connections roughly equals the instance memory in GB multiplied by 100, so always check that ratio when troubleshooting unresponsive Aurora MySQL due to connection spikes.
DBS-C01 Management and Operations Practice Question
This DBS-C01 practice question tests your understanding of management and operations. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 an Amazon Aurora MySQL database. The database experiences a sudden spike in connections and then becomes unresponsive. The DB instance has a db.r5.large class with 8 GB memory. The maximum connections parameter is set to the default. Which is the most likely cause of the unresponsiveness?
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 the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The number of connections exceeded the max_connections limit
Option C is correct because the default max_connections for Aurora MySQL is based on memory, and with 8 GB, it is about 800. A spike exceeding that can exhaust resources. Option A is wrong because storage auto-scaling is seamless. Option B is wrong because burst balance applies to gp2 volumes, but Aurora uses cluster storage. Option D is wrong because replica lag would affect reads, not make the instance unresponsive.
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 DB instance's EBS burst balance dropped to zero
Why it's wrong here
Aurora does not use EBS; it uses cluster storage.
✗
The storage volume ran out of allocated space
Why it's wrong here
Aurora automatically scales storage, so this is unlikely.
✓
The number of connections exceeded the max_connections limit
Why this is correct
Exceeding max_connections can cause the database to reject connections and become unresponsive.
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.
✗
A read replica had high replication lag
Why it's wrong here
Replica lag does not affect the primary instance's responsiveness.
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 DBS-C01 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.
Management and Operations — This question tests Management and Operations — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The number of connections exceeded the max_connections limit — Option C is correct because the default max_connections for Aurora MySQL is based on memory, and with 8 GB, it is about 800. A spike exceeding that can exhaust resources. Option A is wrong because storage auto-scaling is seamless. Option B is wrong because burst balance applies to gp2 volumes, but Aurora uses cluster storage. Option D is wrong because replica lag would affect reads, not make the instance unresponsive.
What should I do if I get this DBS-C01 question wrong?
Identify which DBS-C01 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.
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Question Discussion
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