Bài giảng Romney_ais13 - Chapter 10: Processing Integrity and Availability Controls

Processing Integrity and Availability ControlsChapter 1010-1Learning ObjectivesIdentify and explain controls designed to ensure processing integrity.Identify and explain controls designed to ensure systems availability.10-2Processing Integrity ControlsInputForms designSequentially prenumberedTurnaround documents10-3Processing Integrity: Data Entry ControlsField checkCharacters in a field are proper type Sign checkData in a field is appropriate sign (positive/negative)Limit checkTests numerical amount against a fixed valueRange checkTests numerical amount against lower and upper limitsSize checkInput data fits into the fieldCompleteness checkVerifies that all required data is enteredValidity checkCompares data from transaction file to that of master file to verify existenceReasonableness testCorrectness of logical relationship between two data itemsCheck digit verificationRecalculating check digit to verify data entry error has not been made10-4Additional Data Entry ControlsBatch processingSequence checkTest of batch data in proper numerical or alphabetical sequenceBatch totalsSummarize numeric values for a batch of input recordsFinancial totalHash totalRecord countPromptingSystem prompts you for input (online completeness check)Closed-loop verificationChecks accuracy of input data by using it to retrieve and display other related information (e.g., customer account # retrieves the customer name)10-5Processing ControlsData matchingTwo or more items must be matched before an action takes placeFile labelsEnsures correct and most updated file is usedRecalculation of batch totalsCross-footing Verifies accuracy by comparing two alternative ways of calculating the same totalZero-balance testsFor control accounts (e.g., payroll clearing)Write-protection mechanismsProtect against overwriting or erasing dataConcurrent update controlsPrevent error of two or more users updating the same record at the same time10-6Output ControlsUser review of outputReconciliationProcedures to reconcile to control reports (e.g., general ledger A/R account reconciled to Accounts Receivable Subsidiary Ledger)External data reconciliationData transmission controls10-7Availability ControlsPreventive maintenanceFault toleranceUse of redundant componentsData center location and designRaised floorFire suppressionAir conditioningUninterruptible power supply (UPS)Surge protectionPatch management and antivirus softwareBackup proceduresIncrementalCopies only items that have changed since last partial backupDifferential backupCopies all changes made since last full backupDisaster recovery plan (DRP)Procedures to restore organization’s IT functionCold siteHot siteBusiness continuity plan (BCP)How to resume all operations, not just IT10-8Key TermsTurnaround documentField checkSign checkLimit checkRange checkSize checkCompleteness checkValidity checkReasonableness testCheck digitCheck digit verificationSequence checkBatch totalsFinancial totalHash totalRecord countPromptingClosed-loop verificationHeader recordTrailer recordTransposition errorCross-footing balance testZero-balance test10-9Key Terms (continued)Concurrent update controlsChecksumParity bitParity checkingFault toleranceRedundant arrays of independent drives (RAID)Uninterruptible power supply (UPS)BackupRecovery point objective (RPO)Recovery time objective (RTO)Real-time mirroringFull backupIncremental backupDifferential backupArchiveDisaster recovery plan (DRP)Cold siteHot siteBusiness continuity plan (BCP)10-10