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CISA Practice Question: An e-commerce company stores customer payment…
An e-commerce company stores customer payment card data in a tokenized database. The tokenization system replaces credit card numbers with tokens, and the actual card numbers are stored in a separate, highly restricted vault. The company is audited for Payment Card Industry Data Security Standard (PCI DSS) compliance. During the audit, it is discovered that the tokenization system sometimes fails due to high load, causing the application to fall back to storing actual card numbers temporarily. This fallback mechanism was not documented or approved. The company also uses the same encryption key for the vault as for other non-sensitive data. The auditor identifies several non-compliances. Which of the following should the company prioritize to remediate?
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
✓
Remove the fallback mechanism and ensure the tokenization system has appropriate redundancy
The highest priority is to remove the fallback mechanism (option B) because it directly exposes actual cardholder data when tokenization fails, violating PCI DSS requirement 3.4 to render stored cardholder data unreadable. While using a separate encryption key for the vault (option C) is important, the fallback mechanism represents an immediate and undocumented data exposure risk. Therefore, eliminating this fallback and ensuring redundancy in the tokenization system should be the priority.
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 the tokenization system with end-to-end encryption
Why it's wrong here
End-to-end encryption is a different approach, but the immediate issue is the fallback.
- ✓
Remove the fallback mechanism and ensure the tokenization system has appropriate redundancy
Why this is correct
Eliminating the fallback prevents storage of raw card numbers.
- ✗
Use a separate encryption key for the vault
Why it's wrong here
Key separation is important but secondary to the fallback issue.
- ✗
Increase the capacity of the tokenization server to handle peak loads
Why it's wrong here
This addresses performance, not the fallback flaw.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CISA practice question is part of Courseiva's free ISACA 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 CISA exam.