Layer 2 Ethernet Switches: Understanding their Key Features and Functions

Key Features of Layer 2 Ethernet Switches

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Which three statements accurately describe Layer 2 Ethernet switches? (Choose three.)



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A. B. C. D. E. F.


A. Spanning Tree Protocol allows switches to automatically share VLAN information. This statement is false. Spanning Tree Protocol (STP) is used to prevent loops in a network with redundant paths by blocking certain ports. It has nothing to do with sharing VLAN information between switches. VLAN information is typically manually configured on each switch or automatically learned through protocols such as Cisco's VLAN Trunking Protocol (VTP).

B. Establishing VLANs increases the number of broadcast domains. This statement is true. VLANs create logical broadcast domains by grouping together ports on a switch that belong to the same VLAN. Broadcasts sent by a device in one VLAN are not forwarded to devices in other VLANs, which helps to reduce unnecessary network traffic.

C. Switches that are configured with VLANs make forwarding decisions based on both Layer 2 and Layer 3 address information. This statement is false. Switches make forwarding decisions based solely on Layer 2 information, such as the MAC addresses of devices connected to the switch. Layer 3 information, such as IP addresses, is used by routers to make forwarding decisions between different networks.

D. Microsegmentation decreases the number of collisions on the network. This statement is true. Microsegmentation is the practice of breaking up a larger network segment into smaller segments, typically by configuring each switch port to be its own separate collision domain. By reducing the size of collision domains, the likelihood of collisions decreases.

E. In a properly functioning network with redundant switched paths, each switched segment will contain one root bridge with all its ports in the forwarding state. All other switches in that broadcast domain will have only one root port. This statement is true. In a network with redundant paths, STP is used to prevent loops by blocking certain ports. The switch with the lowest bridge ID becomes the root bridge, and all other switches determine their root ports based on the shortest path to the root bridge. In a properly functioning network, there should be only one root bridge with all its ports in the forwarding state.

F. If a switch receives a frame for an unknown destination, it uses ARP to resolve the address. This statement is false. ARP (Address Resolution Protocol) is used by devices to resolve the MAC address of a device with a known IP address. If a switch receives a frame for an unknown destination, it will flood the frame out all ports (except the port it was received on) in an attempt to reach the destination. If the destination device is not found, the frame is dropped.