The correct action is to replace the failed drive and rebuild the array. This is required because RAID 5 uses distributed parity, meaning parity data is spread across all drives, allowing the array to withstand a single drive failure without data loss. When a drive fails, the array enters a degraded state; replacing the faulty drive triggers the rebuild process, during which the RAID controller reconstructs the missing data from the parity information on the remaining drives, restoring full fault tolerance. On the CompTIA ITF+ FC0-U61 exam, this question tests your understanding of RAID redundancy and recovery procedures—a common trap is assuming you can simply hot-swap without a rebuild, or that RAID 5 can survive multiple simultaneous failures. Remember the memory tip: “One down, rebuild to renown”—RAID 5 tolerates exactly one drive failure, and you must rebuild to regain that protection.
FC0-U61 Infrastructure Practice Question
This FC0-U61 practice question tests your understanding of infrastructure. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 server has four hard drives configured in RAID 5. One drive fails. What must the technician do to restore full redundancy?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Replace the failed drive and rebuild the array
RAID 5 uses distributed parity across all drives, allowing the array to tolerate a single drive failure without data loss. When a drive fails, the technician must replace the failed drive and then rebuild the array, during which the RAID controller reconstructs the missing data from the parity information on the remaining drives. This restores full redundancy by returning the array to a fault-tolerant state.
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.
✗
Replace all drives and reconfigure RAID
Why it's wrong here
Only the failed drive needs replacement; replacing all is unnecessary.
✗
Simply replace the drive with a larger capacity drive
Why it's wrong here
While a larger drive may work, the array must be rebuilt to restore redundancy, not just swapped.
✓
Replace the failed drive and rebuild the array
Why this is correct
RAID 5 can rebuild from parity; replacing the failed drive and initiating rebuild restores fault tolerance.
Related concept
Read the scenario before looking for a memorised answer.
✗
Replace the failed drive and restore from backup
Why it's wrong here
Restoring from backup is not necessary since RAID 5 can rebuild from existing parity.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may think a simple drive replacement automatically restores redundancy, but they must understand that the array must be explicitly rebuilt (either automatically or manually) to regenerate the missing data from parity.
Detailed technical explanation
How to think about this question
During a RAID 5 rebuild, the controller reads parity and data from the remaining drives to XOR-calculate the missing data block by block, writing it to the replacement drive. This process can take hours for large arrays and stresses the remaining drives, increasing the risk of a second failure; some controllers support 'hot spare' drives to automate this. In real-world scenarios, a rebuild failure due to uncorrectable read errors on surviving drives is a known risk, which is why RAID 6 or RAID 10 is preferred for critical data.
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 practitioner preparing for the FC0-U61 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
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.
Infrastructure — This question tests Infrastructure — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Replace the failed drive and rebuild the array — RAID 5 uses distributed parity across all drives, allowing the array to tolerate a single drive failure without data loss. When a drive fails, the technician must replace the failed drive and then rebuild the array, during which the RAID controller reconstructs the missing data from the parity information on the remaining drives. This restores full redundancy by returning the array to a fault-tolerant state.
What should I do if I get this FC0-U61 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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