What input should a DBA use for negative testing on a numerical field restricted between 1 and 100?

• A. Inputting the number -10
• B. Entering a special character, such as '@'
• C. Both of the above
• D. Inputting the number 50

Answer: (C)

For negative testing on a numerical field that is restricted between 1 and 100, it is appropriate to use both a number that falls outside of the specified range and an invalid input like a special character.

Inputting the number -10 is a suitable method for negative testing because it is clearly outside the allowed numerical range, which should trigger validation error messages or prevent the input from being accepted. This type of input tests the robustness of the data validation mechanisms ensuring they effectively prevent unacceptable values.

Entering a special character, such as '@', also serves as a form of negative testing. This tests how the application handles non-numeric characters when the field is expected to receive only integers. Such characters should be rejected or handled gracefully, thus confirming that the system is designed to accept only valid numerical input.

Both inputs are critical in ensuring that the system not only accepts valid entries but also effectively rejects invalid ones, validating the integrity and robustness of the data entry mechanism.