What is the role of server-side verification in UI address form validation?

• A. Server-side checks alone are sufficient
• B. They duplicate client checks
• C. They prevent invalid data from reaching the server
• D. They are unnecessary if client-side is present

Answer: (C)

Server-side verification acts as the final gate for input data. Client-side validation is great for immediate feedback and a smoother user experience, but it runs in the browser and can be bypassed or manipulated. Therefore, the server must re-check everything the user submits to ensure it meets all rules, is properly formatted, and isn’t malicious. This server-side validation protects data integrity and security, ensuring only valid data is processed, stored, or used, even if the UI validation is bypassed. It works alongside client checks, not as a replacement, providing a trustworthy defense against bad input and potential attacks.