mediumMultiple ChoiceObjective-mapped
Most Critical Control for Data Conversion: Reconciliation of Control Totals
A bank is converting data from its legacy core banking system to a new platform. Which control is MOST critical to ensure the completeness and accuracy of data conversion?
Quick Answer
The answer is reconciliation of converted data totals to source system totals because this control directly verifies that every record from the legacy system has been accurately migrated without loss or duplication. By comparing aggregate values such as account balances and transaction counts between the source and target databases, this data conversion reconciliation provides a definitive check for completeness and accuracy that no other control can guarantee. On the Certified Information Systems Auditor CISA exam, this concept tests your understanding of the most critical control during a data conversion project—a common scenario where candidates mistakenly choose input validation or access controls instead. A frequent trap is assuming that parallel testing or data mapping alone suffices, but only reconciliation of control totals catches silent errors like dropped records or double-counting. Remember the mnemonic: “Totals tell the tale—reconcile or fail.”
⚠ Common exam trap
Test-takers frequently confuse 'data validation rules' (which ensure individual field correctness) with 'reconciliation' (which ensures aggregate completeness and accuracy), leading them to choose Option C even though validation cannot detect missing records or totals.
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
✓
Reconciliation of converted data totals to source system totals
Reconciliation of converted data totals to source system totals is the most critical control because it directly verifies that every record from the legacy system has been accurately migrated without loss or duplication. This control compares aggregate values (e.g., account balances, transaction counts) between the source and target databases, providing a definitive check for completeness and accuracy that other controls cannot guarantee.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Parallel running of both systems
Why it's wrong here
Parallel running helps but is not specifically for data conversion accuracy.
- ✓
Reconciliation of converted data totals to source system totals
Why this is correct
Reconciliation directly verifies completeness and accuracy.
- ✗
Data validation rules programmed in the conversion tool
Why it's wrong here
Validation rules alone cannot guarantee completeness.
- ✗
User acceptance testing of the new system
Why it's wrong here
UAT focuses on functionality, not data accuracy.
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Same concept, more angles
1 more way this is tested on CISA
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company is migrating from a legacy system to a cloud-based ERP. Which of the following is the MOST important control to ensure data integrity during data conversion?
easy- A.Automated backup
- B.User acceptance testing
- C.Parallel running
- ✓ D.Reconciliation of control totals
Why D: Reconciliation of control totals is the most important control because it directly verifies that the sum of key fields (e.g., total account balances, record counts) in the source system matches the target cloud-based ERP after conversion. This ensures no data is lost, duplicated, or corrupted during the extraction, transformation, and loading (ETL) process, which is critical for maintaining data integrity in a migration from a legacy system.
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.