Implementing Cisco IP Switched Networks (CCNP SWITCH, legacy) — Question 112

On which layer does IP source guard provide filtering to prevent a malicious host from impersonating the IP address of a legitimate host?

Answer options

• A. Layer 1
• B. Layer 2
• C. Layer 3
• D. Layer 7

Correct answer: B

Explanation

The correct answer is B, as IP source guard operates at Layer 2 of the OSI model, where MAC addresses are used to ensure that only legitimate IP addresses can be associated with specific MAC addresses. Options A, C, and D are incorrect because Layer 1 deals with physical connections, Layer 3 is concerned with routing, and Layer 7 involves application-level protocols, none of which directly handle the IP source filtering functionality provided by IP source guard.