What Is Input Validation?

Input validation checks whether data supplied to an application matches the expected format, type, length, range, and permitted values before the application processes it. Certification exams may present malformed or unexpected user input and ask which secure-development practice can reduce the resulting risk. Applications should treat information from forms, files, cookies, application programming interfaces, headers, and external systems as untrusted. A date field should accept valid dates, a quantity should remain within an approved numeric range, and a filename should reject characters that could alter a file path. Validation should occur on the server because client-side checks can be bypassed. Developers should use allowlists where practical, reject invalid values, limit input size, handle errors safely, and combine validation with output encoding, parameterized queries, and authorization controls rather than treating it as a complete defense. Produced by BareMetalCyber.com, where you’ll find more cyber audio courses, books, and information to strengthen your educational path. Also, if you want to stay up to date with the latest news, visit DailyCyber.News for a newsletter you can use, and a daily podcast you can commute with. And dont forget Cyberauthor.me for the companion study guide and flash cards!