Exam CISSP Topic 3 Question 587 Discussion

Live or actual field data is not recommended for use in the testing procedures because both data types may not cover out of range situations and the correct outputs of the test are unknown. Live data would not be the best data to use because of the lack of anomalies and also because of the risk of exposure to your live data. Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, John Wiley & Sons, 2001, Chapter 7: Applications and Systems Development (page 251).