Certified Ethical Hacker (CEH v6, legacy) — Question 1

A circuit level gateway works at which of the following layers of the OSI Model?

Answer options

• A. Layer 5 - Application
• B. Layer 4 – TCP
• C. Layer 3 – Internet protocol
• D. Layer 2 – Data link

Correct answer: B

Explanation

The correct answer is B, as circuit level gateways function at Layer 4, which is the Transport layer, specifically dealing with TCP connections. The other options are incorrect because Layer 5 pertains to the Application layer, Layer 3 handles Internet Protocol, and Layer 2 focuses on Data link functions, none of which are the operating layers for circuit level gateways.