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WalesComputer ScienceQuick questions
Unit 3 Programming and System Development
Quick questions on Data security, integrity and validation: backup, error detection and encryption - WJEC A-Level Computer Science
3short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is error detection in transmission?Show answer
Transmission can corrupt data, so error-detection methods are added. A parity bit makes the total number of 1s even or odd, as agreed, and the receiver re-checks it. A checksum is a value calculated from the data and sent with it for the receiver to recalculate and compare. A check digit is an extra digit calculated from a number (such as a barcode or ISBN) to catch entry errors.
What is q1?Show answer
State the type of backup that copies only the data changed since the last backup. [1 mark]
What is q2?Show answer
State one limitation of using a single parity bit for error detection. [1 mark]
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