JN0-102 · Question #277
What information is used by a switch to forward an Ethernet frame to its destination?
The correct answer is B. destination MAC address. This question identifies the specific piece of information a Layer 2 switch uses to direct incoming Ethernet frames to their intended recipient.
Question
What information is used by a switch to forward an Ethernet frame to its destination?
Options
- AIP address
- Bdestination MAC address
- CARP table entry
- DFCS checksum
How the community answered
(34 responses)- A6% (2)
- B91% (31)
- D3% (1)
Why each option
This question identifies the specific piece of information a Layer 2 switch uses to direct incoming Ethernet frames to their intended recipient.
An IP address is a Layer 3 address used by routers for forwarding IP packets, not by Layer 2 switches for Ethernet frames.
A Layer 2 switch inspects the destination MAC address in an incoming Ethernet frame header to determine which port to forward the frame out of. It consults its MAC address table (also known as a CAM table) which maps MAC addresses to specific switch ports to make this forwarding decision.
An ARP table entry maps an IP address to a MAC address; a switch directly uses the destination MAC address for forwarding, not the ARP table entry itself.
The FCS (Frame Check Sequence) checksum is used for error detection in an Ethernet frame, not for forwarding decisions.
Concept tested: Switch forwarding logic and MAC addresses
Source: https://www.cisco.com/c/en/us/support/docs/lan-switching/ethernet-technologies/10574-21.html
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