200-301 Question #1302: Real Exam Question with Answer & Explanation

Question

How does frame switching function on a switch?

Options

• Arewrites the source and destination MAC address
• Bforwards frames to a neighbor port using CDP
• Cforwards known destinations to the destination port
• Dis disabled by default on all interfaces and VLANs

Explanation

A Layer 2 switch learns MAC addresses from incoming frames and stores them in its MAC address table, then forwards subsequent frames with known destination MAC addresses only out the specific port associated with that MAC. This ensures efficient, directed delivery of frames.

Common mistakes.

• A. A Layer 2 switch does not rewrite the source and destination MAC addresses in a frame; that action is typically associated with Layer 3 routing or Network Address Translation (NAT).
• B. CDP (Cisco Discovery Protocol) is a proprietary protocol used for neighbor discovery and information exchange, not for forwarding data frames based on MAC addresses.
• D. Frame switching is a fundamental function of a Layer 2 switch and is enabled by default on all interfaces and VLANs to facilitate local network communication.

Concept tested. Layer 2 switch frame forwarding

Reference. https://www.cisco.com/c/en/us/products/collateral/switches/catalyst-6500-series-switches/prod_white_paper0900aecd80404068.html

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