200-150 · Question #27
Which table in a switch must be populated with forwarding information as to reduce Layer 2 flooding in the network?
The correct answer is A. MAC table. A switch reduces Layer 2 flooding by building a MAC address table that maps MAC addresses to specific ports, allowing it to unicast frames directly to the correct destination instead of flooding all ports.
Question
Which table in a switch must be populated with forwarding information as to reduce Layer 2 flooding in the network?
Options
- AMAC table
- Bforwarding table
- CARP table
- Drouting table
How the community answered
(33 responses)- A94% (31)
- B3% (1)
- D3% (1)
Why each option
A switch reduces Layer 2 flooding by building a MAC address table that maps MAC addresses to specific ports, allowing it to unicast frames directly to the correct destination instead of flooding all ports.
The MAC address table (also called the CAM table) is populated as the switch learns source MAC addresses from incoming frames on each port. Once an entry exists, the switch forwards frames only to the port associated with the destination MAC address. Without entries in the MAC table, the switch must flood frames out all ports except the ingress port, increasing unnecessary traffic across all segments.
The term 'forwarding table' is a generic label and does not specifically identify the Layer 2 data structure a switch uses to make port-based forwarding decisions.
The ARP table resolves IP addresses to MAC addresses at Layer 3 and is maintained by end hosts and routers, not used by switches for making Layer 2 frame forwarding decisions.
The routing table is a Layer 3 construct used by routers to select paths between IP networks, and plays no role in a switch's Layer 2 forwarding process.
Concept tested: Switch MAC address table reducing Layer 2 flooding
Source: https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/lanswitch/configuration/xe-16/lanswitch-xe-16-book/lsw-fwd-layer2.html
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