The answer is to use Amazon EBS io2 Block Express volumes with provisioned IOPS. This choice directly improves MongoDB failover reliability on EC2 by ensuring the secondary node can replay the oplog and catch up to the primary’s write operations with minimal latency, reducing the window for data staleness and preventing the degraded performance seen after a crash. On the AWS Certified Database Specialty DBS-C01 exam, this scenario tests your understanding of how storage performance impacts replica set elections and oplog replay speed, often appearing as a trap where candidates mistakenly choose ephemeral instance stores or snapshot-based solutions. A common memory tip is to think “IOPS for Oplog”—high and consistent IOPS from io2 volumes directly accelerate the secondary’s catch-up process, whereas instance stores risk data loss and snapshots are backup tools, not performance enhancers.
DBS-C01 Monitoring and Troubleshooting Practice Question
This DBS-C01 practice question tests your understanding of monitoring and troubleshooting. 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 is running a self-managed MongoDB cluster on Amazon EC2. The cluster consists of three replica set members in different Availability Zones. The primary node recently experienced a crash, and the cluster failed over to a secondary. However, the new primary is showing significantly higher latency. The operations team wants to ensure that failover is fast and consistent. What should be done to improve the failover reliability?
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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use Amazon EBS io2 Block Express volumes with provisioned IOPS.
Option C: Using Amazon EBS io2 Block Express volumes with higher IOPS and lower latency can reduce the time for the secondary to catch up. Option A: EBS Multi-Attach is not supported for io2? Actually io2 supports multi-attach but for shared volumes, not typically used for MongoDB. Option B: Using instance store volumes may have higher performance but are ephemeral and data loss is possible. Option D: Snapshots are for backups, not for improving failover performance.
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.
✓
Use Amazon EBS io2 Block Express volumes with provisioned IOPS.
The clue word "primary" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use Amazon EBS Multi-Attach to allow all replicas to share the same volume.
Why it's wrong here
Multi-Attach is for shared volumes but MongoDB does not support shared storage.
✗
Switch to instance store volumes for better I/O performance.
Why it's wrong here
Instance store is ephemeral and data is lost on stop/termination, not suitable for production databases.
✗
Configure EBS snapshots to be taken every 5 minutes.
Why it's wrong here
Snapshots are for backup, not for improving failover speed.
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
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
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.
Monitoring and Troubleshooting — This question tests Monitoring and Troubleshooting — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use Amazon EBS io2 Block Express volumes with provisioned IOPS. — Option C: Using Amazon EBS io2 Block Express volumes with higher IOPS and lower latency can reduce the time for the secondary to catch up. Option A: EBS Multi-Attach is not supported for io2? Actually io2 supports multi-attach but for shared volumes, not typically used for MongoDB. Option B: Using instance store volumes may have higher performance but are ephemeral and data loss is possible. Option D: Snapshots are for backups, not for improving failover performance.
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: "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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This DBS-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 DBS-C01 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.