(ISC)2 Certified in Cybersecurity Practice Exam

What is the purpose of a checksum in digital data?

1. To encrypt the data for security

2. To compress the data for storage

3. To detect errors in the data

4. To categorize the data sensitivity

The correct answer is: To detect errors in the data

A checksum is a calculated value that is derived from a set of data, and its primary purpose is to detect errors in that data. When data is transmitted or stored, a checksum is generated by summing the binary values of the data in a specific way. This value is then sent or stored alongside the data itself. Upon receipt or retrieval, the checksum can be recalculated based on the received or retrieved data. By comparing the newly calculated checksum with the original, one can identify whether any changes or errors have occurred during transmission or storage. If the checksums match, it is likely that the data has remained intact and unchanged. If they do not match, it indicates that the data may have been corrupted, altered, or experienced an error, prompting further investigation or the need for data recovery. The alternative choices provided do not serve the same function as a checksum. For example, encryption is focused on securing data against unauthorized access, while compression aims to reduce the amount of storage space required. Additionally, categorizing data sensitivity relates to classification rather than verifying integrity. Therefore, the role of a checksum distinctly emphasizes error detection in digital data.