How a Switch Performs Frame Switching

Describe switching concepts

Answer Correct answer: A — On receiving a frame, the switch looks up the destination MAC in its MAC address table to find the outgoing interface.

What is a characteristic of frame switching?

performs a lookup to learn the destination interface Correct Answer
disabled by default on all interfaces and VLANs
buffers and forwards frames with less than 5 CRCs
protects against denial of service attacks

Community Votes

100%

100% of anonymous learners picked answer A. Votes are pick records left by other test-takers — they are not the verified answer.

Community Insight

Frame switching = destination-MAC lookup in the MAC table for the egress port. MAC learning (populating the table) happens on the SOURCE MAC; forwarding uses the DESTINATION MAC.

A Layer 2 switch forwards frames by looking up the destination MAC in the MAC address table (CAM table) to select the egress port. It does not rewrite MAC addresses, is not disabled by default, and floods—not drops—unknown destinations.

Picking B (learning is enabled by default, not switching), C (CRCs are dropped, the '<5 CRC' phrasing is nonsense), or D (DoS is unrelated).

Community Discussion (6 comments)

picho707 👍 5 Selected: A

Frame switching is a process used in networking where data is divided into packets known as frames and transmitted across the network. When a frame arrives at a switch, the switch looks at the destination MAC address and performs a lookup in its MAC address table to learn the destination interface. The switch then forwards the frame to its destination.

lmmujsi 👍 1 Selected: A

A characteristic of frame switching is A. performs a lookup to learn the destination interface. Frame switching involves receiving a frame and using the destination MAC address within that frame to determine the appropriate output interface where the frame should be sent. This process is essential for directing frames to their intended destinations on a network

d5c03de 👍 1 Selected: A

A is correct.

NINJA777 👍 1

B. performs a lookup to learn the destination interface. Frame switching involves examining the destination MAC address of an incoming frame and performing a lookup in a forwarding table to determine the outgoing interface to which the frame should be forwarded. This process allows the switch to efficiently forward frames based on their destination addresses without needing to rewrite MAC addresses, send retransmission requests, or inspect and drop frames from unknown destinations.

Rolfer 👍 2 Selected: A

A is correct.

JulesAZ 👍 1 Selected: A

As Q 1317 Thanks to Picho for the actual explanation.

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Expert Analysis

Why the Answer Is Correct

A is correct. Frame switching performs a lookup of the destination MAC in the MAC address table to determine the outgoing interface, then forwards the frame out that port (or floods if unknown).

Why the Other Options Are Wrong

B is wrong: it is MAC learning, not frame switching, that is enabled by default. C is wrong: corrupt frames are dropped, and the 'buffered with less than 5 CRCs' wording is meaningless. D is wrong: DoS protection is unrelated to basic frame switching.

Community Comment Notes

The vote is A (100). Commenters confirm the switch examines the destination MAC and looks it up in the forwarding table to pick the egress port, noting it does not rewrite MAC addresses.

Official Reference

https://learningnetwork.cisco.com/s/ccna-exam-topics

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