Which testing method is used when the tester has zero knowledge of the target system before testing?

• A. Black-Box Testing
• B. White-Box Testing
• C. Gray-Box Testing
• D. Penetration Testing

Answer: (A)

When you have no knowledge of the internal workings of a system before testing, you’re testing from an external perspective. Black-box testing treats the system as a black box and focuses on what it does rather than how it does it. Testers interact with the system through its visible interfaces (like user input, APIs, or UI) and verify that outputs, responses, and behavior align with requirements, under both expected and edge-case conditions. This approach simulates real-world use and external attack-like scenarios without peeking at the internal code or design.

White-box testing, by contrast, relies on full knowledge of the internal structure, code, and logic. Gray-box testing uses some partial internal knowledge. Penetration testing is a broader activity that may use various levels of prior knowledge, but the zero-knowledge, externally-focused approach described here is best captured by black-box testing.