Question 55 of 144
SK0-005 security-disaster-recovery Practice Question
A medium-sized company uses a backup strategy that includes a full backup every Sunday at 2:00 AM and differential backups Monday through Saturday at 2:00 AM. The backups are written to a network-attached storage (NAS) device. On Thursday morning, the company experiences a ransomware attack that encrypts all data on the file server, including the NAS. The administrator needs to restore the file server with minimal data loss. The last successful full backup was from the previous Sunday, and differential backups were successful on Monday, Tuesday, and Wednesday. However, Thursday's differential was not completed because the attack occurred before the scheduled time. The administrator attempts to restore using the Sunday full backup and Thursday's differential, but the restore fails because the differential backup on the NAS is also encrypted. Which of the following is the best course of action?
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
✓
Restore from the Sunday full backup and Wednesday's differential backup
The most recent clean backup set is Sunday's full plus Wednesday's differential, as both were taken before the ransomware attack. Restoring from these will recover data as of Wednesday's backup, minimizing data loss. Using only Wednesday's differential requires the full backup first. Paying the ransom is not recommended and may not work. Reinstalling the OS and restoring from cloud would not apply because cloud was not mentioned.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Pay the ransom to decrypt the differential backup
Why it's wrong here
Paying the ransom is not a recommended security practice and may not result in decryption.
- ✓
Restore from the Sunday full backup and Wednesday's differential backup
Why this is correct
This is the most recent complete and uncorrupted backup set, providing the best recovery point.
- ✗
Reinstall the operating system and restore files from cloud storage
Why it's wrong here
There is no indication that cloud storage is available, and this would not utilize existing backups.
- ✗
Restore using only Wednesday's differential backup
Why it's wrong here
Differential backups require the last full backup to be restored first; they are incremental from the full, not standalone.
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Last reviewed: Jul 26, 2026
This SK0-005 practice question is part of Courseiva's free CompTIA 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 SK0-005 exam.
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